US 5737403

Patent Overview: US 5,737,403

Title: Interaction of routing features in a telephone system
Patent number: US 5,737,403 A
Inventor: Pamela Zave
Original/current assignee: AT&T Inc. (originally assigned to AT&T CORP.)
Application number: US 08/528,900
Priority/filing date: 1995-09-15
Publication (grant) date: 1998-04-07
Legal status (as listed): Expired – Lifetime (anticipated expiration 2015-09-15)
Source: https://patents.google.com/patent/US5737403/en

Purpose: The invention concerns "routing features" in telephone systems—functions where the system automatically does something with a call directed to a given telephone other than simply setting it up. Routing features such as call forwarding and call blocking can conflict when combined (e.g., a forwarded number is itself forwarded, or forwarding intersects with Do Not Disturb or Originating Call Screening). The patent addresses how such features should behave when they interact, framing the problem around the human situations motivating subscribers rather than arbitrary or negotiated choices.

Plain-language scope: The disclosed solution classifies routing features into two classes. A telephone feature applies to a telephone number representing a telephone; a subscriber feature applies to a telephone number representing a subscriber. Call forwarding splits accordingly: "follow-me" forwarding treats the forwarded-to number as a specific telephone, while "delegate" forwarding treats it as a pointer to a person. Routing proceeds by determining, at each routing step, whether each relevant feature is a telephone feature or a subscriber feature, and routing accordingly—so, for example, follow-me forwarding does not follow the forwarded-to number's own forwarding features, whereas delegate forwarding does. Similar logic distinguishes telephone-feature blocking from subscriber-feature blocking. Figures 1–9 illustrate forwarding and forwarding-with-blocking examples and tabular embodiments.

What the excerpt does not establish: The supplied text is partial (it ends mid-sentence) and omits the claims and detailed description. It therefore does not establish the exact claim scope, the full finite-state-automaton implementation details, or any prior-art analysis. Nothing here should be read as a legal conclusion on validity, ownership, or status.