Damn!...No Dial Tone?

Red landline phone

In 2001, telephone users in some areas were experiencing dead phone lines due to circuit congestion of unknown origin. This was more than annoying: as many as 90 calls dealing with life-threatening situations were effected each day.

AT&T research scientist and IMA visitor V. Ramaswami led a group to study this problem using stochastic models. Their research pinpointed the causes of the congestion, particularly the role of very long calls associated with internet dial-ups, and developed remedies that could be applied in both the short and long term. The modeling not only saved lives, but also identified opportunities for major cost savings, estimated at $15M per year, to AT&T and has resulted in multiple patents. The 2005 paper "Assuring Emergency Services Access: Providing Dial Tone in the Presence of Long Holding Time Internet Dial-Up Calls," was an INFORMS Wagner prize finalist. The collaborative research of Guy Latouche and Ramaswami at the IMA provided key methodologies for this work. Ramaswami credits the role of the IMA's quiet but highly charged atmosphere, ideal for serious work that requires collaboration and uninterrupted concentration.