US 5,329,578 · Granted 1994-07-12

How Northern Telecom Patented Your Idea of a Smart Phone Number

Imagine having one phone number that follows you everywhere—to work, home, or your friend's house—and automatically routing calls based on who's calling and what time it is. This 1994 patent describes exactly that system, where a central hub reads your preferences and decides where each call should actually ring.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a telecommunications system where a single personal phone number connects to a central service node that stores a subscriber's routing preferences in a database. What's protected is the method of receiving incoming calls to that personal number, looking up the subscriber's stored profile (which specifies rules based on caller identity, time of day, and urgency), and then automatically redirecting the call to the appropriate destination—whether that's a mobile phone, office, or voicemail. The invention specifically protects the combination of the personal number, the service node, the database storage of preferences, and the logic that applies those preferences to route each individual call.

Why it matters

This patent captures an early vision of what would eventually become essential mobile phone features: call routing, voicemail integration, and caller-based call handling. Filed in 1992 and granted in 1994, it predates the widespread adoption of personal mobile devices and cellular networks. The patent is significant because it describes the infrastructure and logic that later enabled features like call forwarding, priority calling, and do-not-disturb modes—functionality that became standard in modern phones and cloud-based phone services. Northern Telecom was a major telecom equipment supplier, and this patent reflects the industry's early thinking about how to manage incoming communication as people became increasingly mobile.

Real-world use

When you set your iPhone to silence calls from unknown numbers after 9 PM, or when your Android phone automatically sends certain callers to voicemail based on a custom rule you created, you're using the exact concept this patent describes—a central system applying your stored preferences to each incoming call.

Original USPTO abstract

A system for providing personal communication services (PCS) is described, wherein a subscriber can tailor the telephone service to provide communication mobility and incoming call management. Calls to a personal number assigned to the subscriber are routed to a PCS service node which will re-route the call according to the subscriber's service profile stored in a database. The service node insures that attempts to communicate with the subscriber are handled with appropriate consideration for who is calling, when the call is made, and the urgency of the call. In addition, the subscriber is given control over how the system will work for them in routing incoming calls.

Patent details

Publication number: US 5,329,578
Filing date: 1992-05-26
Grant date: 1994-07-12
Assignee: Northern Telecom Limited
Inventor(s): BRENNAN; PAUL M., MARK; RAYMOND M.
CPC class: H04W8/18

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