But such confidence in IP-based infrastructure runs against the grain of a growing list of providers that have decided to pursue packet telephony via the DSL and ATM route. As IP takes on the functions of ATM, we'll be in a position to exploit that. The ATM gear Nortel supplied to Sprint performs a function called subcell multiplexing, a technique that Thurman says fills up empty spaces in the ATM cell with fragments from IP voice packets, thereby conserving bandwidth. In June, the two partners conducted the first publicly announced test of VoDSL service, which took place in New York City. Everything is on schedule for commercial launches at the start of next year.
Competitors see that as a major market opportunity for delivery of combined voice and data services.
Primary is using VoDSL products from Lucent. Primary is looking to strike partnerships with other competitors to combine its DSL strengths with their switching facilities to create what it hopes will be a formidable challenge to incumbent telcos. To be offered as a first-line service, any telephony offering must demonstrate that it can deliver a dial tone to customers even during events such as electricity outages. Rhythms' Kelley says trials so far have found VoDSL service to be far more reliable than originally anticipated, which means it could well be offered as a first-line service with appropriate powering backup. He adds that businesses already are accustomed to bundling data and voice over T1 lines while using regular circuit-switched lines as a lifeline backup, so VoDSL should not be a problem for these customers.