Princeton-Rutgers Seminar Series in Communications and Information Theory

Title: Providing Dial Tone in the Presence of Circuit Congestion due to Long Holding Time Internet Dial-Up Calls - Assuring Emergency Services Access.

Speaker: Vaidyanthan Ramaswami, AT & T

Date: November 13, 2003, 4:30 - 5:30pm

Location: Princeton University, E-Quad-B205, Princeton, NJ


Telephone availability is critical, particularly in emergency situations where immediate help is needed. Imagine a scenario where you need to call 911 for help for a heart attack victim or for a larger catastrophe and find the telephones dead. This work describes how queueing models and techniques were used to identify the root cause of dial tone unavailability in significant parts of the AT&T network and to develop remedies restoring quality service protecting the AT&T brand name and assuring the safety of its customers. Several counter-intuitive results defying conventional wisdom on the greater efficacy of larger server groups as well as the applicability of established insensitivity theorems for circuit blocking are demonstrated. These have wider implications far beyond circuit switched telephony and point to some interesting areas for further research.