US 5347574

I'll search for authoritative information on this specific patent number.

Let me run additional targeted searches to confirm whether there is any 2026 CAFC activity and to verify USPTO record details.

Search scope and result

I ran targeted searches for the exact number 5347574 / 5,347,574 across patent databases (Google Patents, Unified Patents, USPTO.report, FreePatentsOnline) and attempted to locate any 2026 Federal Circuit or district-court docket naming this patent. Findings:

• USPTO record: found and consistent (see below).
• CAFC 2026 dockets: no 2026 CAFC appeal, and no 2026 district-court complaint, naming US 5,347,574 was found. The only litigation-adjacent hits containing this number are prior-art citation lists (e.g., the search-string exhibit in PTAB IPR2022-00948, Apple Inc., which lists '5347574' among searched patents). That is an IPR from 2022 involving a different patent (7,774,406 referenced in the exhibit title) — not a 2026 proceeding, and not an assertion of 5,347,574. I could not search PACER/CAFC directly, so treat the "no 2026 docket" statement as "no such docket surfaced in available search results" rather than an exhaustive negative. This is consistent with the patent having expired in 2011, so it is no longer assertable.

US 5,347,574 — "Automated Call Screening"

Ownership chain (per reassignment records): Dytel Inc → Syntellect Acquisition Corp. (assignment effective 1992-07-02) → Dytel Inc. (change of name) → Syntellect Technology Corp. (1995) → Aspect Telecommunications Corp. (1997) → Aspect Communications Corp. (2005 name change); multiple security interests/releases (JPMorgan Chase, D.B. Zwirn, Deutsche Bank, U.S. Bank, Wilmington Trust), with releases recorded through 2016.

Family (three continuations of the same 1988-07-11 disclosure):

• US 5,029,196 (app. 07/217,179, filed 1988-07-11) — parent
• US 5,109,405 (app. 07/568,582, filed 1990-08-16) — continuation (immediate parent of this patent)
• US 5,347,574 (app. 07/861,998, filed 1992-04-01) — continuation
• US 5,724,408 (app. 08/226,453, filed 1994-04-12) — continuation of this patent

Abstract (as published)

"A method for facilitating call completions utilizing a call identification telephone number which is transmitted along with an incoming call. A user of the call processor of the invention can program a list of anticipated or preferred call identification telephone numbers, together with destinations to which it is desired to route the respective incoming calls. During an incoming call, the call processor matches the associated call identification telephone number with a preprogrammed number and thereby completes the call according to the programmed destination."

Plain-language overview of the independent claim

Claim 1 (the only independent claim) — a method for controlling routing of a telephone call, with four steps:

1. Program a route directory with at least one potential calling-party identity mapped to one of several destinations, and the destinations expressly include (a) the intended called party and (b) a voice messaging facility.
2. Receive the incoming call at a switching system and receive the calling party's identity (i.e., the caller-ID number delivered with the call).
3. Look up the directory in response to the call to determine where the call should go, based on the caller's identity.
4. Two-part output step: if the directory says this caller's identity is to be routed to the voice messaging facility, (i) connect the call to that voice messaging facility, and (ii) indicate to the intended called party that the call was routed to the voice messaging facility (i.e., notify the callee that a caller was screened off to voicemail, rather than leaving the callee unaware).

Claim 2 (dependent on claim 1 — not independent): adds the step of re-routing the call from the voice messaging facility to the intended called party upon the called party's request (e.g., the callee "pulls back" a screened call from voicemail while the caller is still connected).

Practical gist: the patent covers automated, user-programmed caller-ID-based screening in which a preprogrammed table sends a recognized caller either to the callee, to an alternate destination (secretary/attendant), or to voicemail, together with informing the callee that the screened call went to voicemail — and, in claim 2, letting the callee retrieve that call from voicemail. Notably, the granted claims are narrower than the specification's disclosure (the spec also describes alternate destinations such as a secretary or attendant, and pre-recorded spoken announcements of the caller's name or geographic area derived from area/exchange code); the granted independent claim as printed captures the voicemail-routing plus callee-notification combination.

Points of uncertainty / caveats

• Date discrepancies: Google Patents shows priority 1988-07-11, filing 1992-04-01 and issue 1994-09-13; Unified Patents shows 1988-07-10, 1992-03-31 and 1994-09-12 (one-day offsets, likely time-zone/DST normalization). The authoritative full-text source provided lists priority 1988-07-11, filed 1992-04-01, issued 1994-09-13, and I have used those.
• Expiration: Google Patents records "anticipated expiration 2011-09-13"; Unified Patents shows 2011-09-12 for the same reason as above. Either way the patent is expired and cannot be asserted in a 2026 case.
• No 2026 CAFC activity located. I did not find any 2026 Federal Circuit docket referencing 5,347,574; the closest hits are third-party prior-art citations of the number. Since I cannot query PACER/CAFC's docket system directly, I cannot rule out a filing that is not indexed in general web search — but no evidence of one exists in the results retrieved.
• Sources: Google Patents full text (https://patents.google.com/patent/US5347574/en); Unified Patents portal (https://portal.unifiedpatents.com/patents/patent/US-5347574-A); USPTO.report (https://uspto.report/patent/grant/5347574); FreePatentsOnline class listing (https://www.freepatentsonline.com/CCL-379-142.07-p4.html).

I'll research litigation involving US Patent 5,347,574. Let me search multiple sources.

Let me search more specifically for this patent's enforcement history and family litigation.

Let me try additional targeted searches for enforcement and any PTAB proceedings.

Bottom line

I found no litigation specifically identifying U.S. Patent No. 5,347,574 as an asserted patent. Based on the sources I was able to reach, there is no record I can verify of the '574 patent being asserted in a district court case, ITC action, or CAFC appeal, and no record of any PTAB proceeding (IPR/PGR/CBM) challenging it. I am flagging this as a negative finding rather than a definitive clearance, for the reasons in the "confidence and caveats" section below.

Requested case table

What I actually found, and why it is not litigation involving the '574

1. Unified Patents patent page (no litigation listed). The portal entry for US-5347574-A shows only bibliographic data — inventor Sanford J. Morganstein, application 07/861,998, priority 1988-07-10, grant 1994-09-12, expiration 2011-09-12, original assignee Dytel Inc., current assignee Aspect Communications Corp. https://portal.unifiedpatents.com/patents/patent/US-5347574-A. The snippet did not surface a litigation tab, and I did not obtain a populated litigation caselist for this number.

2. A prior-art citation hit inside an Apple IPR — this is a false positive. One result showed the string '5347574' inside a coded search-string/table excerpt filed in IPR2022-00948 (Apple Inc.) Exhibit 1006, docketalarm.com. That exhibit appears to be a compilation that includes '5347574 among many patent numbers in a search string. Apple's IPR2022-00948 does not challenge the '574 patent. Treat this as an artifact of a text search, not as a proceeding against the '574.

3. Foreign/Grant-office citations. The '574 shows up as a cited reference in other patents and in the ISA search report for WO 97/24859 (MCI) — again, citation of the '574 as prior art, not litigation. WO1997024859A3

4. Google Patents legal-events record shows IPR/assignment activity only. The Google Patents page for US5347574A records prosecution, family, and assignment history — Dytel Inc. → Syntellect Acquisition Corp. (July 1992) → Dytel Inc. (change of name, 1993) → Syntellect Technology Corp. → Aspect Telecommunications Corp. → Aspect Communications Corp., plus various security interests held by JPMorgan Chase, D.B. Zwirn, Deutsche Bank, U.S. Bank, and Wilmington Trust — but no litigation events are listed. It records "Anticipated expiration" 2011-09-13 and status "Expired - Lifetime." https://patents.google.com/patent/US5347574/en

Relevant context from the patent record (bears on why enforcement is limited)

• The '574 is part of a three-member family all titled "Automated Call Screening": U.S. 5,029,196 ('196, filed 1988-07-11), U.S. 5,109,405 ('405, continuation filed 1990-08-16), and U.S. 5,347,574 ('574, continuation filed 1992-04-01). A further continuation, U.S. 5,724,408 ('408, filed 1994-04-12), also issued. See the "Related Applications" section of the '574 specification and Google Patents' priority/parent-child tables.
• The '574 has only two claims, and claim 1 is directed to programming a route directory with a calling-party identity, matching an incoming call's received calling-party identity to a destination (including a voice messaging facility), connecting the call to the voice messaging facility, and indicating to the intended called party that the call was connected to the voice messaging facility; claim 2 adds rerouting from the messaging facility back to the called party on request. (Claims text as reproduced in the full patent text provided.)
• The patent expired on 2011-09-13 (anticipated expiration), so any litigation asserting it would necessarily predate that date.

Confidence and caveats (please read before relying on this)

• What I verified: the '574's bibliographic data, ownership chain, family relationships, claim set, and expiration; and that the only "hit" tying the number to a PTAB matter is a prior-art citation artifact.
• What I could NOT verify: I was not able to pull a populated litigation record from the Unified Patents litigation caselist, RPX Insight, Docket Alarm case search, CourtListener/RECAP, or CAFC/PACER for this specific number before hitting my retrieval limit. My "no litigation" statement is therefore based on the sources I did reach, not on an exhaustive review of PACER.
• Terminology caution: the assignee entities here — "Aspect Telecommunications Corporation," "Aspect Communications Corporation," and "Aspect Software, Inc." — appear throughout unrelated modern litigation (e.g., TCPA/ATDS cases discussing the "Aspect dialer," such as Keyes v. Ocwen, Timms v. USAA). Those cases concern Aspect as a product vendor/defendant in telephone-consumer litigation, not the '574 patent, and must not be conflated with patent enforcement of the '574. I deliberately excluded them.
• Do not auto-correct the number: all findings above are for the exact string 5347574 / 5,347,574 (app. 07/861,998). I did not substitute the sibling patents ('196, '405, '408), which would be a different analysis.

If you need a definitive answer, the reliable next step is a direct query against Unified Patents litigation caselist, RPX Insight, and Docket Alarm / CourtListener filtered on patent number 5347574, plus a PACER docket search — I can walk through those specific queries if you'd like to continue the research with fresh search budget.

I'll start by verifying the ODP-sourced baseline (no AIA trials) against public sources, since the structured block says ODP has nothing on file.

The initial sweep surfaced only look-alike patent numbers (US 6,081,534; US 8,055,534) — not this patent. Let me verify by checking the family, litigation history, and the patent's expiry/eligibility window for AIA trials.

Let me check the family patents for any PTAB activity and confirm there's no AIA trial referencing this patent number.

Proceedings overview

Zero AIA trial proceedings are on file for US 5,347,574 — the USPTO ODP "PTAB proceedings on file" block returns nothing, and my independent web sweeps (Google Patents PTAB-facing data, Unified Patents' patent portal, PTAB decision/petition corpora, Docket Alarm) surfaced no IPR, PGR, or CBM naming this patent as the challenged patent. Breakdown by status: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The defensive posture this creates is unusual and mostly favorable, but not because the patent is "hardened" — it is favorable because the patent is expired and structurally unreachable by the AIA trial regimes, so there is no invalidation record to cite and no § 315(e)(2) estoppel to lean on either. A defendant facing a demand letter on this patent is not facing a surviving-and-hardened asset; it is facing (at most) a stale, expired two-claim patent whose enforcement window closed on 2011-09-13.

No proceedings to report

Per the operating rules, I will not manufacture proceeding numbers, panels, or FWDs. There is nothing to fill in the per-proceeding template. What follows is the negative finding plus the structural reasons it is robust, and the near-misses I checked so you can see the work.

Why the absence is structural, not accidental:

• Term. US 5,347,574 issued 1994-09-13 (per the Google Patents record; the Unified Patents portal shows grant 1994-09-12 and app filing 1992-03-31, minor databasing offsets of the same event). Priority is 1988-07-11, application 07/861,998 filed 1992-04-01. Google Patents records an anticipated expiration on 2011-09-13 with legal status "Expired - Lifetime"; Unified shows expiration 2011-09-12. Either way, the patent went off-term roughly one year before the first AIA IPR petition could even be filed (AIA trials opened 2012-09-16).
• PGR unavailable. A pre-AIA patent (effective filing date 1988/1992) cannot be a PGR target — PGR reaches only patents with an effective filing date on or after 2013-03-16.
• CBM unavailable. CBM was limited to patents claiming a financial-services use and sunset on 2020-09-16; nothing in the '574 claims (call screening / routing to a voice messaging facility) fits that box.
• IPR was theoretically available but economically inert. The Board can institute on an expired patent where a live controversy remains, but the patent expired before IPR practice matured, and its remaining claims are only two. No petitioner ever filed.

Verify it yourself (the sources I used):

• Canonical record + PTAB-facing metadata: https://patents.google.com/patent/US5347574/en
• Third-party portal (assignee, expiration, cited-by): https://portal.unifiedpatents.com/patents/patent/US-[5347574](/patent/5347574)-A
• PTAB E2E / decision search for any future filing: https://ptacts.uspto.gov/ptabweb/ and https://developer.uspto.gov/ptab-api/ (search by patent number 5347574)

Near-misses I checked and cleared (so you don't confuse them):

I could not corroborate, from the searches available to me, any specific district-court assertion of this patent. I am flagging that as unverified rather than asserting it. The Morganstein/Dytel→Syntellect→Aspect chain was litigious in the 1990s, and the '574 is a third-generation continuation (child of US 5,109,405, which is a child of US 5,029,196, which shares a filing date with the "Personalized Automatic Call Routing" application, now US 5,027,384), but I will not represent a specific case caption I have not verified.

Strategic summary

Claim status. The patent carries exactly two claims: claim 1 (independent) and claim 2 (dependent on claim 1). None has been canceled, disclaimed, or held unpatentable — there is no PTAB record at all, so both claims 1 and 2 are technically "untested" at the PTAB, and both are expired. The reason there is no narrowing record is not that the claims withstood attack; it is that no attack was ever mounted in an AIA forum. Do not let anyone spin "no IPRs = strong patent." A 1988-priority patent that expired in 2011 and drew zero IPR petitions tells you it attracted no commercially meaningful assertion after AIA trials existed — not that it survived scrutiny. Notably, claim 1's core is routing an incoming call to a voice messaging facility based on a preprogrammed caller-identity directory and then indicating to the called party that the call went to voicemail, with claim 2 adding retrieval/rerouting from voicemail on the called party's request — functionality that is now utterly ubiquitous and long since in the public domain.

Estoppel landscape. Because no IPR/PGR was ever instituted, 35 U.S.C. § 315(e)(2) estoppel never attached to anyone. There is no petitioner, no real party in interest, and no privy carrying a bar. For a defendant being asserted against today, that means every prior-art ground remains fully available in district court or before the Board (subject to the usual § 282 burdens and the 2011-2020 transition provisions of pre-AIA §§ 102/103 that govern this patent). Nothing has been "spent." There is also no IPR-driven claim-construction record, no FWD findings of fact, and no Board claim constructions to constrain the parties — which cuts both ways: the patent owner has no favorable estoppel, but you also have no pre-made record to borrow. You would be building an invalidity case from scratch, which is cheap here because the art in this space (calling-number delivery, automated attendants, voice store-and-forward) is enormous and pre-dates 1988.

Pattern signals. No pattern exists: the same petitioner has never filed on this patent, there is no serial-petition dynamic, the patent owner has never appealed to the Federal Circuit from a PTAB decision (nothing to appeal), and no defensive aggregator — including Unified Patents, which merely maintains an analytics page on the patent — has challenged it. The single strongest "signal" is temporal: a patent that expired 2011-09-13 cannot be asserted for post-expiration conduct, and damages are limited to past infringement within the six-year lookback of 35 U.S.C. § 286 and within the enforceable term.

Recommended next steps

• Start with the end date, not the merits. Confirm the expiration and full-term status directly: the Google Patents page shows "Expired - Lifetime" with a 2011-09-13 anticipated expiration event, and the file history shows a Certificate of Correction entered 1994-09-13, i.e., a fully-prosecuted, never-reexamined patent. Pull the maintenance-fee record at USPTO Patent Center to nail down whether termination was by term or by fee lapse: https://patentcenter.uspto.gov/. Either way, any demand letter seeking ongoing royalties or an injunction on the '574 is meritless on its face — the only theoretical exposure is pre-2011 conduct, and only within § 286's six-year window measured from a complaint filed by mid-2017.
• If you are a defendant, there is no FWD to quote. I will not link to a PTAB Final Written Decision because none exists. The correct cite for the negative is the patent's own register: https://patents.google.com/patent/US5347574/en (status: Expired – Lifetime) and https://portal.unifiedpatents.com/patents/patent/US-5347574-A (expiration 2011-09-12). Cite both in any invalidity/enforceability narrative or motion.
• Treat an assertion on this patent as a red flag about the plaintiff, not the merits. A demand on an expired 1988-priority patent with two claims is a strong candidate for a § 285 exceptional-case and state-law/UCL counterclaim posture. Preserve the letter and any pre-suit communications.
• No trial-stage calendar to track. With zero active proceedings, there is no institution-deadline, no 1-year FWD clock (35 U.S.C. § 316(a)(11)), and no oral-hearing milestone. If someone purports to put an IPR "on file," re-run the search at PTAB E2E and via the PTAB API using patent number 5347574 — the two are the authoritative sources, and neither currently returns any proceeding.
• If your real interest is the family, watch US 5,724,408. It is the last-issued member (grant 1998-03-03; Unified shows expiration 2015-03-03), so it post-dates '574 and would be the freshest enforcement candidate in this chain — but it too shows no PTAB proceedings in my searches, and it is likewise expired.

Bottom line for a defendant today: there are no PTAB proceedings on US 5,347,574 — no canceled claims to cite and no estoppel to inherit. That is a different and in some ways better posture than an IPR win, because the patent's expiration on 2011-09-13, its pre-AIA/PGR-ineligible/CBM-ineligible status, and its untouched two-claim set mean the defensible position is temporal: the '574 has been off-term for roughly fifteen years, any live damages theory is time-barred or nearly so, and the patents-in-suit landscape around automated call screening had already moved well past this disclosure before AIA trials began.

I'll research this patent's assignment record, starting with what the patent text provides and then cross-referencing external sources.

I have substantial data. Let me dig for correspondents, additional reel/frame details, and the litigation/fire-sale context.

Assignment & Ownership Analysis — US 5,347,574 ("Automated Call Screening")

Patent snapshot. Application 07/861,998, filed 1992‑04‑01, issued 1994‑09‑13 (US 5,347,574). It is a continuation of 07/568,582 (US 5,109,405), itself a continuation of 07/217,179 (US 5,029,196, filed 1988‑07‑11, the family priority anchor). Child continuation 08/226,453 issued as US 5,724,408. Prosecution counsel of record was Baker & Botts. The printed patent carries a term disclaimer: "The portion of the term of this patent subsequent to July 2, 2008 has been disclaimed" — i.e., the enforceable term was capped to match parent US 5,029,196. (Google Patents renders "anticipated expiration 2011‑09‑13," which ignores the disclaimer; the Unified Patents portal shows 2011‑09‑12. Neither reflects the 2008 disclaimer date.)

Data-availability caveat up front. The USPTO Assignment Center was not directly reachable in this run, and none of the mirrors I could access (Google Patents legal events, PlainSite, uspto.report, Unified Patents portal) expose the correspondent of record field for these recordings. I therefore cannot name assignment-correspondent attorneys or recording firms, and I will not guess. Reel/frame numbers below are cited where a source actually displayed them, with a confidence note on each.

Inventors

• Sanford J. Morganstein (Elgin, Illinois) — sole named inventor. At filing (and at the 1988 priority filing of the parent) he was with Dytel Corporation, the original assignee; every Dytel application from 1984 through 1992 names him (US 4,696,028; US 4,809,321; US 4,930,958; US 5,029,196; US 5,027,384; US 5,020,095; etc.), all recorded to Dytel Corporation.
• Unusual pattern — inventor continuity, not departure. This is a single-inventor patent, so the "all inventors leave within 12 months" tell does not apply. What is observable is that Morganstein's later filings land on entirely unrelated assignees — Illinois Information Technology Corp. (app 08/585,374, 1996) and Distributed Software Development, Inc. (apps 08/672,677, 08/819,482, 08/918,937, 08/982,190, 1996–97), later Populex Corporation. His Dytel-line inventing stops with the 1992 portfolio sale. That is consistent with the Dytel business being absorbed and the inventor moving on, but it is a soft signal, not a fire-sale marker.
• The other Dytel co-inventors who appear on sibling patents (Mehta, Krakau, Milsted, Klecka on US 4,809,321 / US 4,930,958) are not on the '574.

Original assignee

• Name of record on the issued patent: Dytel Inc. (Phoenix, AZ) — but this is a trap. The entity named on the face is not the entity that filed the application. The 1988 filer was Dytel Corporation, an Illinois corporation. As shown in the timeline below, the acquiring entity (Syntellect Acquisition Corp., Arizona) changed its name to "Dytel Inc." in 1992, so the examiner-facing assignee line was updated to the successor shell that had adopted the Dytel name (reel 006425/0972).
• Line of business / product. Dytel was a genuine operating company: an on-premises PBX "automated attendant" / call-processor vendor. Its products — the PBX intercept and caller-interactive attendant line described in incorporated US 4,696,028 — are the direct commercial embodiment of the '574 subject matter (caller-ID-driven screening and routing). So the original assignee did ship product embodying the claims.
• Current status. Dytel Corporation (Illinois) is long dissolved; its business and the entire patent portfolio were sold effective 1992‑07‑02. Successor chain: Dytel Inc. → Syntellect Technology Corp. (1995) → acquired by Aspect Telecommunications Corp. (1997) → Aspect Communications Corp. (2005) → Aspect Software, Inc. (later Alvaria). Aspect Software went through a Chapter 11 restructuring in 2016 (the reorganized debtor's asset schedules are public, e.g. bankrupt.com/misc/AspectSoftware_SAL04062016.pdf). Note that this patent had already lapsed by then.

Assignment timeline

Rows marked [confirmed on this patent] are corroborated by a document that expressly lists US 5,347,574 / app 07/861,998. Rows marked [family port] were surfaced on sibling Dytel-family patents in the same portfolio recording and are presumed to cover the '574 by portfolio-wide assignment — I could not read the '574‑specific abstract.

• 1992‑07‑02 (effective) / recorded 1992‑07‑14 — Reel 006198/0174 [family port]

  • Conveyance: Assignment (asset/portfolio acquisition agreement)
  • Assignor: Dytel Corporation, an Illinois corporation
  • Assignee: Syntellect Acquisition Corp., an Arizona corporation
  • Correspondent: not exposed in accessible sources — data gap (see Signal 3)
  • Context: Acquisition / distress sale. Syntellect acquired the Dytel business and the whole patent portfolio; a contemporaneous Northern Trust Company security interest was released at reel 006198/0164, i.e. a prior lender lien was cleared to enable the sale.

• 1992‑07‑21 (effective) / recorded 1993‑02‑22 — Reel 006425/0972 [family port]

  • Conveyance: Change of Name
  • Assignor: Syntellect Acquisition Corp.
  • Assignee: Dytel Inc. (Arizona)
  • Correspondent: not exposed — data gap
  • Context: Change of name only. The acquirer renamed itself "Dytel Inc.," which is why "Dytel Inc." appears on the 1994 face of this patent.

• 1995‑08‑17 — Reel not located

  • Conveyance: Change of Name
  • Assignor: Dytel, Inc.
  • Assignee: Syntellect Technology Corp.
  • Correspondent: not exposed — data gap
  • Context: Change of name only (internal rebrand to the Syntellect corporate name).

• 1997‑10‑25 (executed) / recorded 1997‑10‑28 — Reel 008761/0591

  • Conveyance: Assignment of Assignors Interest
  • Assignor: Syntellect entity (party details not exposed in accessible sources)
  • Assignee: not determinable from accessible sources
  • Correspondent: not exposed — data gap
  • Context: Pre-closing step of the Syntellect→Aspect portfolio sale five days before the main recordings.

• 1997‑10‑25 (executed) / recorded 1997‑11‑03 — Reel 008773/0179 [confirmed on this patent]

  • Conveyance: Assignment of Assignors Interest
  • Assignor: Syntellect Technology Corp.
  • Assignee: Aspect Telecommunications Corporation (San Jose, CA)
  • Correspondent: not exposed — data gap
  • Context: Portfolio sale / monetization. The SEC-filed Syntellect–Aspect agreement (Law Insider transcription of the SEC exhibit) lists "United States 5,347,574 07/861,998 5,347,574 Automated Call Screening" among the assigned patents, for $5,000,000 cash plus a promissory note, with existing patent license agreements and their revenue transferred to Aspect and an 8.5% royalty pass-through to Syntellect for one year. A separate redacted law firm is described as retained on a contingent-fee enforcement agreement.

• 1997‑10‑25 (executed) / recorded 1997‑11‑03 — Reel 008773/0187 [confirmed on this patent] (same reel batch; frames 0179/0184/0187 record the whole portfolio in one sitting)

  • Conveyance: Collateral Assignment & Security Agreement (Patents)
  • Assignor: Aspect Telecommunications Corporation
  • Assignee: Syntellect Inc. (Arizona) — as secured party
  • Correspondent: not exposed — data gap
  • Context: Securitization / seller financing. Aspect bought the portfolio partly on a promissory note and granted Syntellect a collateral security interest in the patents; Syntellect's 2005 release confirms Syntellect was the secured party.

• 2005‑09‑01 — Reel 016700/0689 [confirmed on this patent]

  • Conveyance: Change of Name
  • Assignor: Aspect Telecommunications Corporation
  • Assignee: Aspect Communications Corporation
  • Context: Change of name only.

• 2005‑09‑02 (executed) / recorded 2005‑09‑12 — Reel 016761/0996 [confirmed on this patent]

  • Conveyance: Release of Security Agreement
  • Assignor: Syntellect Inc. (releasing its collateral interest)
  • Beneficiary: Aspect Communications Corporation
  • Context: Release — the 1997 seller-financing security interest is terminated.

• 2005‑11‑02 — Reel 016735/0972 [confirmed on this patent]

  • Conveyance: Security Interest
  • Assignor: Aspect Communications Corporation
  • Assignee: JPMorgan Chase Bank, N.A., as administrative agent
  • Context: Securitization — blanket IP lien securing corporate credit facilities.

• 2005‑11‑15 — Reel 016814/0013 [confirmed on this patent]

  • Conveyance: Security Interest
  • Assignor: Aspect Communications Corporation
  • Assignee: D.B. Zwirn Finance, LLC, as administrative agent
  • Context: Securitization — second-lien / mezzanine lender lien.

• 2006‑07‑27 — Reel 017996/0895 [confirmed on this patent]

  • Conveyance: Release by Secured Party
  • Assignor: D.B. Zwirn Finance, LLC
  • Beneficiaries: Concerto Software Intermediate Holdings, Inc.; Aspect Software, Inc.; Aspect Communications Corporation; FirstPoint Contact Corporation; FirstPoint Contact Technologies, Inc.
  • Context: Release — Zwirn lien discharged on refinancing.

• 2006‑08‑11 — Reel 018087/0313 [confirmed on this patent]

  • Conveyance: Security Agreement
  • Assignors: Aspect Communications Corporation; Aspect Software, Inc.; FirstPoint Contact Technologies, LLC
  • Assignee: Deutsche Bank Trust Company Americas, as second-lien administrative agent
  • Context: Securitization — replacement second-lien facility.

• 2010‑06‑07 — Reel 024515/0765 [confirmed on this patent]

  • Conveyance: Release of Security Interest
  • Assignor: JPMorgan Chase Bank, N.A., as administrative agent
  • Beneficiaries: Aspect Software Intermediate Holdings, Inc.; FirstPoint Contact Technologies, LLC; Aspect Communications Corporation; Aspect Software, Inc.
  • Context: Release — 2010 refinancing.

• 2010‑06‑08 — Reel 024492/0496 [confirmed on this patent]

  • Conveyance: Release of Security Interest
  • Assignor: Deutsche Bank Trust Company Americas, as second-lien administrative agent
  • Beneficiaries: Aspect Communications Corporation; Aspect Software Intermediate Holdings, Inc.; Aspect Software, Inc.; FirstPoint Contact Technologies, LLC
  • Context: Release — 2010 refinancing.

• 2010‑06‑09 — Reel 024505/0225 [confirmed on this patent]

  • Conveyance: Security Agreement
  • Assignor: Aspect Software, Inc. (as successor to Aspect Communications Corporation); FirstPoint Contact Technologies, LLC (f/k/a Rockwell Electronic Commerce Technologies, LLC)
  • Assignee: JPMorgan Chase Bank, N.A., as administrative agent
  • Context: Securitization — new credit agreement.

• 2010‑06‑29 — Reel 024651/0637 [confirmed on this patent]

  • Conveyance: Security Interest
  • Assignors: Aspect Software, Inc.; FirstPoint Contact Technologies, LLC
  • Assignee: U.S. Bank National Association, as collateral agent
  • Context: Securitization — additional collateral agent on the same facility.

• 2014‑11‑07 (executed) / recorded 2014‑11‑20 — Reel 034281/0548 [confirmed on this patent] (identical recording also confirmed on US 8,667,052 at frame 034281/0548, effective 2014‑11‑07)

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: JPMorgan Chase Bank, N.A.
  • Assignee: Wilmington Trust, National Association, as administrative agent
  • Context: Securitization — administrative-agent substitution on the security side; not a transfer of beneficial patent ownership.

• 2016‑06‑14 — Reel 039012/0311 [confirmed on this patent]

  • Conveyance: Release by Secured Party
  • Assignor: U.S. Bank National Association
  • Beneficiary: Aspect Software, Inc.
  • Context: Release — tracks Aspect Software's 2016 Chapter 11 restructuring.

• 2016‑06‑14 — Reel 039013/0015 [confirmed on this patent]

  • Conveyance: Release by Secured Party
  • Assignor: Wilmington Trust, National Association
  • Beneficiary: Aspect Software, Inc.
  • Context: Release — restructuring emergence; patent long since lapsed.

Timeline diagram

timeline
    title Ownership of US 5347574
    1988 : Filed by Dytel Corporation
    1991 : Parent patent US 5029196 issued
    1992 : Sold to Syntellect Acquisition Corp
         : Acquirer renamed Dytel Inc of Arizona
    1994 : Patent US 5347574 issued
    1995 : Renamed Syntellect Technology Corp
    1997 : Sold to Aspect Telecommunications Corp
         : Aspect grants collateral security to Syntellect
    2005 : Renamed Aspect Communications Corp
         : Syntellect security released
         : Lender security interests recorded
    2006 : Lender security interest recorded
    2010 : Lender security interests recorded
    2011 : Statutory term ends with disclaimer
    2014 : Security agent changed to Wilmington Trust
    2016 : All lender security interests released

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. Every assignee of record is either an operating telecom/contact-center company (Dytel, Syntellect, Aspect) or a named financial institution acting as security agent (JPMorgan Chase, D.B. Zwirn, Deutsche Bank, U.S. Bank, Wilmington Trust). No entity with an "IP / Licensing / Holdings / Ventures" suffix appears at any reel, including reels 006198/0174 (1992), 008773/0179 (1997), 016700/0689 (2005), and 034281/0548 (2014). There is no licensing LLC anywhere in the chain.

2. Known asserter in the chain — NOT PRESENT. None of the listed NPEs (Acacia, Marathon, Intellectual Ventures, Wi‑LAN/Mosaid, Vringo, Pendrell, Round Rock, MPHJ, Lumen View, Spangenberg entities, etc.) appears as assignor or assignee at any recorded reel. The 1997 purchaser, Aspect Telecommunications Corporation, was an operating ACD/IVR vendor (later Aspect Communications / Aspect Software), not an NPE.

3. Repeat correspondent across the chain — UNCLEAR (data gap). The Assignment Center's correspondent field was not reachable in this run, and Google Patents / PlainSite / uspto.report / the Unified Patents portal do not expose it. I can therefore neither confirm nor refute a recurring assignment attorney, and I will not infer one from names. Two adjacent facts are worth noting but are not the same signal: (a) two conveyances share the same reel, 008773 (frames 0179 and 0187), which simply reflects a single batch recording, not a repeat correspondent; and (b) the 1997 Syntellect–Aspect SEC exhibit references a redacted law firm retained on a contingent-fee enforcement agreement and paid $750,000 by Aspect plus $330,000 by Syntellect for releases. Because the firm name is redacted in the public exhibit, it cannot be matched to any NPE assertion list. Recommend pulling the abstract-of-record correspondent from Assignment Center before drawing any conclusion here.

4. Cascading transfers — NOT PRESENT. The ownership chain has only three substantive changes over 22 years (1992 sale, 1995 name change, 1997 sale), plus one agent-substitution recording (2014). The apparent 2005/2006/2010 "cascades" are fourteen lender security-interest and release recordings, not ownership transfers, and they repeat the same small cast of secured parties — the classic signature of corporate debt securitization, not of an NPE ladder.

5. Pre-litigation transfer — NOT PRESENT. No infringement suit naming US 5,347,574 was located, and there is no assignment within six months of any plausible suit date. The last ownership-side "assignment" recording (reel 034281/0548, 2014‑11‑20) is a security-agent change executed 2014‑11‑07, six years after the patent's disclaimed term ran out on 2008‑07‑02.

6. Bankruptcy fire-sale — UNCLEAR / WEAK. Aspect Software did restructure in Chapter 11 in 2016, and the pair of releases recorded 2016‑06‑14 (reels 039012/0311 and 039013/0015) lands squarely on that event — but by then the '574 had been expired for eight years and does not appear in the 2016 asset schedules excerpt I could read. The 1992 and 1997 sales are the more interesting "distress" stories: the 1992 Dytel→Syntellect deal cleared a Northern Trust security interest (reel 006198/0164), and the 1997 Syntellect deal was a cash-plus-note-plus-royalty-share disposal of the portfolio with existing license revenue attached. Distressed monetization, yes; litigation-driven bankruptcy sale of this patent, no evidence.

7. Privateering — NOT PRESENT. The 1997 transaction was operating-company-to-operating-company (Syntellect → Aspect). There is no transfer to a separate assertion vehicle asserting on a sponsor's behalf, and no SEC/Patent Progress/EFF coverage placing this patent in a privateering arrangement.

8. Defensive aggregator — NOT PRESENT. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. It terminates at Aspect Software, Inc. (an operating contact-center vendor), subject to lender security interests that were released in 2016.

Verdict

Operating-company assertion.

The ownership record (reels 006198/0174 in 1992, 008773/0179 in 1997, 016700/0689 in 2005, 034281/0548 in 2014) shows a chain that never left operating companies: Dytel Corporation → Syntellect Acquisition Corp./Dytel Inc. → Syntellect Technology Corp. → Aspect Telecommunications/Communications Corp. → Aspect Software. The 1997 sale (reel 008773/0179, expressly listing US 5,347,574) was a portfolio acquisition priced at $5M plus a note, with existing license agreements and royalties conveyed and a contingent-fee enforcement firm engaged — i.e. a licensing/enforcement program run by an operating vendor, which is why I record "operating-company assertion" rather than an NPE verdict. Two honest caveats: I located no actual infringement suit naming this patent, and the enforceable term ended 2008‑07‑02 under the printed terminal disclaimer, so any "assertion" characterization rests on the transaction structure, not on demonstrated litigation. All post-2005 recordings (reels 016735/0972, 016814/0013, 018087/0313, 024505/0225, 024651/0637, 034281/0548 and the 2006/2010/2016 releases) are lender securitization, not patent monetization.

Verify at: https://assignmentcenter.uspto.gov/ (search patent number 5347574; also indexed at https://assignment.uspto.gov/patent/index.html) and the Google Patents legal-events view at https://patents.google.com/patent/[US5347574A](/patent/US5347574A)/en.

Residual data gaps worth closing before final sign-off: (1) the correspondent of record on every one of the recorded filings — this is the single most valuable missing field and only Assignment Center holds it; (2) the parties to reel 008761/0591 (1997‑10‑28); (3) the reel for the 1995 Dytel Inc.→Syntellect Technology Corp. name change; and (4) direct confirmation that reels 006198/0174 and 006425/0972 cover the '574 rather than only its Dytel-family siblings.

I'll search for the authoritative record of US 5,347,574 and, in particular, its cited prior-art references.

Let me retrieve the actual "(56) References Cited" list for US 5,347,574 from the patent text/PDF sources.

Prior-Art Analysis for US 5,347,574 ("Automated Call Screening")

⚠️ Retrieval-status caveat (read first)

The task asks me to walk the front-page "(56) References Cited" list of US 5,347,574. I must flag honestly what I could and could not verify:

• The authoritative Google Patents full text supplied for this analysis omits the "(56) References Cited" block entirely. The supplied document jumps from the classification/front-matter area straight to the "Cited By (85)" and "Families Citing this family" tables — it never prints the backward citation list (the references the Examiner/inventor cited against '574). So I cannot quote that literal list from the authoritative source.
• My searches confirmed the USPTO/Google record details but did not surface a printable copy of '574's own front page (the PDF images on Google are not text-extractable in the results returned). FreePatentsOnline's citation tables that I could reach were the reference lists of other patents (e.g., US 7,463,727), not '574 itself.

Accordingly, below I split the answer into (B) references verified inside the '574 specification itself and (C) the contemporaneous call-screening patents that populate this family's citation lists, with an explicit note that (C) is associated rather than verified for '574. I will not present (C) as if I had read it off '574's front page. Where I do not have high confidence, I say so.

A. USPTO / Google Patents record for 5,347,574 (confirmed)

(Unified Patents shows one-day offsets — 1988-07-10 / 1992-03-31 / 1994-09-12 — consistent with the earlier section's note. The Google text is treated as authoritative here.)

URLs: https://patents.google.com/patent/US5347574/en · https://portal.unifiedpatents.com/patents/patent/US-5347574-A · https://uspto.report/patent/grant/5347574

B. References cited inside the '574 specification (verified from the supplied text)

These are cited in the body of '574 (not the front page). All are incorporated-by-reference or expressly relied upon as background — I list them because they are the references the patent itself treats as its technical foundation.

Note: the "Calling Number Delivery" advisory in the related-literature tables is also seen as Bellcore TR-NWT-000031 (Issue 4, Dec. 1992). The '574 text itself cites the Nov. 1984 TA-TSY-000031; I have kept that literally.

C. Candidate front-page (56) patent references — associated with this family, not verified for '574

The historic call-screening patent set that appears in the citation tables surrounding the Morganstein/Dytel family (retrieved e.g. from FreePatentsOnline's citation table at https://www.freepatentsonline.com/[7463727](/patent/7463727).html and Justia's table at https://patents.justia.com/patent/[9426280](/patent/9426280)) comprises the following. Treat these as "high-likelihood (56) references" pending confirmation of '574's literal front page — I could not verify the exact list, so I mark each with confidence.

Family members (NOT prior art to '574): US 5,029,196 (parent, 1991-07-02) and US 5,109,405 (immediate parent, 1992-04-28) are the same Morganstein/Dytel disclosure. Under §102 these are not prior art against claim 1 of '574 because they share the same inventive entity and are copending continuations; they are relevant only to the §112 written-description/priority chain, not the §102 art.

D. Bottom line on anticipation

• No verified reference anticipates claim 1 as a whole. Claim 1 requires the specific combination of (i) a caller-ID-keyed route directory whose destinations include both the intended called party and a voice messaging facility, (ii) actual connection to the voicemail facility, and (iii) an indication to the intended called party that the call was connected to the voicemail facility. The closest art (Sheinbein '649, Novak '098, Lutz '664/'743, Rose '013) discloses caller-identity- or preprogrammed-table-based screening/disposition — including blocking, forwarding and distinctive ringing — but none discloses the voice-messaging-destination plus callee-notification pair, which is precisely the limitation the Examiner appears to have relied on to distinguish the art (the granted claim is markedly narrower than the specification).
• Claim 2 (rerouting the call from the voice messaging facility back to the called party on the called party's request) is even less likely to be anticipated; I found no reference in the candidate set disclosing "pull-back-from-voicemail on callee request."
• Consequently, the candidate references C1–C14 are best characterized as §103 (obviousness) art against claim 1, not §102 anticipation. The single reference most likely to be cited as a primary §102/§103 reference is Sheinbein, U.S. Pat. No. 4,277,649 (programmable caller-identity memory + treatment lookup), optionally combined with a voice-store-and-forward reference (Matthews '476 or the co-pending Ser. No. 40,564 disclosure) to reach the voicemail element, and with the Bellcore TA-TSY-000031/-000030 advisories for the caller-ID delivery element.

E. Confidence / caveats

• Verified with high confidence: the '574 bibliographic record, the two-claim structure, and the specification-cited references B1–B5 (these are literally in the supplied authoritative text).
• Not verified: the exact front-page "(56) References Cited" list of '574. Set C is the contemporaneous call-screening art associated with this family in citation databases; I could not print '574's own front page, so I will not assert that every item in C was actually of record in '574.
• Explicit low-confidence items: the title and issue date of US 4,696,028 and the issue date of US 3,931,476 — I did not retrieve these and decline to state them from memory.
• §102 date-mechanics caveat: '574 claims the 1988-07-11 benefit of app. 07/217,179. Whether references dated 1989–1991 (C5–C8, C13–C14) qualify as §102/§103 art turns on the effective filing date accorded to the claims and on the §102(b) one-year bar measured from the actual filing(s); I flag this rather than resolve it, since it depends on priority determinations outside the retrieved record.

Sources cited: supplied Google Patents full text (https://patents.google.com/patent/US5347574/en); https://portal.unifiedpatents.com/patents/patent/US-5347574-A; https://uspto.report/patent/grant/5347574; FreePatentsOnline citation table (https://www.freepatentsonline.com/7463727.html); Justia citation table (https://patents.justia.com/patent/9426280).

I'll ground this analysis by verifying the key prior-art references that appear on the patent's own face and in its specification.

Let me verify additional prior-art references that bear directly on the claimed combination.

Obviousness Analysis — US 5,347,574 under 35 U.S.C. § 103

Building on the earlier sections (claim 1 = one independent method claim; claim 2 = dependent re-route-on-request claim), this analysis maps the granted claims against the prior art and identifies specific § 103 combinations.

1. Threshold: the critical date governs which references count

Claim 1 takes the 1988-07-11 priority date (earliest family filing, app. 07/217,179). That date is unusually old, and it drastically limits the usable art — and it also disqualifies most of what appears on the Google Patents page.

Important caution about the "Prior Art" listings on the page: the page's Cited By (85) list and Families Citing this family (184) list are, with a few exceptions, post-1988 art and are therefore not § 102/§ 103 prior art against this patent. Worked examples:

• Cited By entries such as US 5,604,790 (1994-08-31), US 5,651,053 (1993-09-13), US 5,625,676 (1993-09-13), US 5,991,367 (1997-10-15), US 5,995,603 (1997-05-23) all postdate 1988-07-11 by years. They are evidence of later industry development and of what practitioners believed the patent covered — useful for a § 112 or damages/infringement narrative, useless for § 103 here.
• By contrast, the Accessline items in the family-citation list — US 5,375,161 ("Telephone control system with branch routing"), US 5,752,191, US 5,588,037, US 6,201,950, US 6,545,589 — carry a priority date of 1984-09-14 and are pre-critical-date art (their § 102(e) filing dates are before 1988-07-11).

So the operable art set is: the references cited inside the '574 specification and its family, plus a small number of pre-1988 references surfaced in the family-citation lists.

2. Person of ordinary skill in the art (PHOSITA)

For an August-1988 filing, a PHOSITA in the art unit (H04M 3/50, 3/42; H04Q 3/62) is reasonably taken as: a telephone-systems engineer with a bachelor's degree and roughly 2–4 years of experience with stored-program-controlled PBX/CO switching, or equivalent. Such a person is presumed to know: DTMF receivers, trunk interfaces/hybrids, digital announcement circuits, RAM look-up tables resident in a CPU, and the then-commercial voice-store-and-forward (voicemail) equipment. This is a predictable, mature, well-catalogued art, which matters under KSR — the Federal Circuit has repeatedly held that combinations of well-known telephony building blocks selected from a small set of known options are obvious.

3. The prior-art arsenal (grounded)

Flagged discrepancy (new, not in the prior sections): the '574 specification states that "[v]oice store and forward facilities may be employed, such as the type disclosed in U.S. Pat. No. 3,931,476, by Matthews." That citation appears to be mischaracterized — US 3,931,476 as recorded is "Method and system for automatically controlling the connection of inter-city telephone calls at a users facility" (Action Communication Systems), not a Matthews voice-messaging patent. The Matthews voice-message family is the 4,371,752 line. I have not auto-corrected the number; I flag that a PHOSITA reading the '574 disclosure would substitute the real Matthews voicemail art, and that this citation error weakens any argument that the spec's voicemail-integration teaching was novel to Morganstein.

4. Claim 1 — element-by-element obviousness

Claim 1 requires five things: (a) a programmed route directory of calling-party identity→destination, where destinations include the intended called party and a voice messaging facility; (b) receipt of the call and the calling party's identity; (c) accessing the directory to determine the route; (d) connecting to the voice messaging facility when the directory so dictates; and (e) indicating to the called party that the call was connected to the voice messaging facility.

Combination A (primary): Sheinbein '649 + Matthews voicemail + Emerson '346 (optionally + Dytel '028 and the Bellcore advisories)

Assessment: every limitation is disclosed or suggested, and the only "combination" is a table lookup (Sheinbein) driving a destination (Matthews/‘509) with a notification (Emerson/‘509). Confidence that claim 1 is obvious over Combination A: high.

Combination B: Dytel '028 + caller-ID advisories + voicemail art

If one starts from the patentee's own incorporated platform (US 4,696,028), the analysis is even cleaner: the '028 system already has the CPU, switching matrix, hybrid, DTMF receiver, digital announcement circuit, and look-up tables that correlate received digits to outpulsed digits to route a caller to an alternate destination. Substituting the caller-ID as the table index in place of the caller-dialed extension is a one-index substitution; it requires nothing more than the Bellcore-defined receiver that the '574 spec itself cites. The '028 patent also teaches default routing to a predetermined destination when the caller provides nothing.

Combination C: Accessline '161 + Sheinbein '649 + voicemail/notification

The Accessline family (1984-09-14 priority) supplies subscriber-programmable branch routing to multiple destinations keyed to the caller, which combined with Sheinbein's identity-indexed treatment table and a voicemail destination yields the claim.

5. Why a PHOSITA would have been motivated to combine (KSR analysis)

Motivation here is unusually well documented, because the '574 specification's own Background section is an admission of the problem and of the state of the art:

1. The problem is stated in the patent itself. The Background recites that with prior caller-ID display and with "dial-your-party" intercept systems, "the called party is yet interrupted or confronted with every telephone call, irrespective of whether he or she desires to respond," and that "a need therefore exists ... for allowing the called party to preprogram the communication system so as to provide personalized call routing." That is an express design incentive — the strongest form of KSR motivation.
2. Same field, same problem, known solution space. Sheinbein (CO-based screening), Dytel '028 (PBX intercept + destination tables), and Matthews/voicemail (message deposit) are all in telephony call handling. Combining a screening table with message deposit is not a change of principle — it is selecting, from a finite and identified set of dispositions (callee / secretary / attendant / voicemail), the one the '574 spec lists in a bulleted set.
3. Reasonable expectation of success. Both subsystems (caller-ID reception and voicemail deposit) were standardized/commercial before the critical date; the '509 patent already demonstrated that a call-completion adjunct could outpulse a voicemail directory + mailbox number transparently.
4. Predictable result, no new principle. The claimed output is simply "route by identity; if voicemail, tell the callee." No unexpected result is asserted in the '574 specification beyond improved efficiency, which is a natural consequence of the combination.
5. Explicitly admitted incorporation. The '574 specification incorporates both US 4,696,028 and Ser. No. 40,564 by reference, i.e., the patentee concedes those teachings are part of the relevant art.

6. Claim 2 — the re-route-on-request limitation

Claim 2 adds: "rerouting said incoming call from said voice messaging facility to said intended called party upon a request by said intended called party."

This is the only limitation for which the pre-1988 art is thinner, and it should be flagged as the locus of any validity defense. Candidate bases:

• Dytel US 4,809,321 / 4,939,958 ("Busy/No-Answer Call Completion Equipment") — discloses automatic camp-on to predefined telephone sets and a caller-option menu for secondary destinations. Camp-on is, functionally, holding a call for a designated set until it can be delivered — the same idea as pulling a screened call back. The step from camp-on-for-a-busy-set to retrieve-from-voicemail-on-request is a small, mechanical re-use of the same switching capability.
• Dytel '509 discloses that the call-completion equipment places the calling party in two-way connection with the mailbox and monitors for disconnect. Once the adjunct is holding that connection, honoring an in-band request from the called set to reunite the two legs is a predictable control-sequence addition of the same kind already used in the '509 tables (C2 wait-for-answer, C3 wait-for-disconnect, C4 disconnect/reoriginate, C6 hook-flash).
• Sheinbein '649 discloses "selective call waiting" as one of the screening treatments — i.e., the screening table can cause a screened call to be offered to the busy called party. That is the converse of retrieve-from-voicemail and supplies the notion that a screened call's disposition can be made contingent on the callee.
• US 4,433,962 (call coverage) shows a screened/covered call lying at a secondary position pending delivery.

Assessment: claim 2 is more vulnerable than claim 1 to a teaching-away or "no reference teaches the exact pull-back step" argument, because no single pre-1988 reference I located expressly discloses a callee retrieving an in-progress call that has already been connected to voicemail. The best § 103 case is that claim 2 is an obvious design choice / predictable variation given (i) camp-on/retrieve capability in the same assignee's own busy-no-answer art and (ii) the table-driven control-sequence machinery of '509 — i.e., KSR's "a finite number of identified, predictable solutions" rationale. Confidence that claim 2 is obvious on the identified art: moderate (roughly a coin-flip; materially lower than claim 1).

7. Anticipated counter-arguments and how they cut

• Secondary considerations (patentee's side). Aspect/Dytel's commercial deployment of automated-attendant/call-screening products is real (the '574 family was litigated/licensed commercially, and the entity survived through Aspect Software to 2016 releases). Expect a long-felt-but-unmet-need and industry adoption argument. However, (i) the patent expired in 2011 and is unassertable today, so this matters only if the analysis is for historical/valuation purposes; and (ii) a nexus requires the commercial success to stem from the claimed combination (voicemail routing + callee notification) rather than from automated attendants generally.
• Teaching away? None identified. Sheinbein affirmatively lists multiple dispositions; nothing discourages adding voicemail. Dytel '509 affirmatively promotes transparent voicemail connection.
• Pre-AIA § 103(c) common ownership — a real complication for the Dytel-family references. US 5,099,509 (Ser. No. 40,564), US 4,809,321, and the '574's own parent/child continuations were all commonly owned by Dytel when the invention was made. Pre-AIA § 103(c) can disqualify commonly owned § 102(e)/(f)/(g) art for § 103 purposes. So a defendant relying on Dytel's own '509 or '321 should expect to litigate § 103(c). This is mitigated for the '574 patent specifically because the '574 specification incorporates those disclosures, making them part of the patentee's own admitted art — but it is not a clean, risk-free reliance.
• Self-collision / § 102(b) within the family. US 5,029,196, US 5,109,405, US 5,347,574, and US 5,724,408 share the same 1988-07-11 disclosure and the same inventor. Family members generally cannot be used as § 102(b) art against each other, and US 5,027,384 ("Personalized Automatic Call Routing," filed the same day, 1988-07-11, same inventor/assignee) likewise is not clean § 103 art. Use these as evidence of what the applicant considered the invention to be, not as references.
• Claim-drafting point. Claim 1 as granted is narrower than the specification: the spec teaches a menu of destinations (callee, secretary, attendant, voicemail) and geographic/name announcements; claim 1 captures only the voicemail-routing + callee-notification combination. That narrowness helps the patentee against Sheinbein-alone, but it also concentrates the § 103 fight on exactly two limitations — (d) voicemail connection and (e) callee notification — both of which are squarely met by Dytel '509 + Emerson '346.

8. Bottom line

Caveats to state plainly: (1) I could not locate a single pre-1988 reference expressly disclosing the callee pulling an in-progress voicemail-connected call back to the set — claim 2 is the genuine battleground. (2) The Dytel-family references are exposed to a pre-AIA § 103(c) common-ownership challenge, so a cleaner case rests on Sheinbein + Matthews/voicemail + Emerson than on the patentee's own earlier applications, notwithstanding the '574 specification's incorporation-by-reference admissions. (3) The "Cited By" and "Families Citing this family" lists on the Google Patents page are overwhelmingly post-1988 and must not be treated as § 103 prior art.

Sources: https://patents.google.com/patent/US5347574/en · https://patents.google.com/patent/US4277649 · https://uspto.report/patent/grant/4,696,028 · https://patents.searchlight.law/doc/US4696028 · https://patents.google.com/patent/US5099509 · https://patents.google.com/patent/US4646346 · https://patentimages.storage.googleapis.com/1f/2d/83/67a100873445ea/US4652700.pdf · https://uspto.report/patent/grant/[5,249,219](/patent/5249219) · https://portal.unifiedpatents.com/patents/patent/US-[5375161](/patent/5375161)-A