Following our newsletter last week about AT&T's new IP-Multimedia Subsystem (IMS)-based VoIP offering, we heard back from several readers and this week we'd like to share their replies along with our commentary. The first comment came from John via e-mail about AT&T's selection of other IMS suppliers (we had mentioned Alcatel-Lucent). John cited information from other sources that the AT&T VoIP solution included third-party technology, and that the offer was essentially a proprietary solution which he believed could lead to patent disputes like those encountered by Vonage.

To John’s first question about other suppliers, we know there are many suppliers involved in delivering AT&T’s new VoIP service. For example, the ability to see call records on a TV screen controlled by a media server is via software supplied by Microsoft. The ability to connect a VoIP call to the legacy PSTN will likely require the cooperation of at least half-a-dozen vendors. But IMS is an architectural model designed so vendors with different components can have a reference for interoperability. In the case of AT&T, Alcatel-Lucent is the primary supplier of the IMS core, stemming from the 2005 decision by SBC to adopt Lucent. (Historical note: since 2005, SBC, BellSouth, and Cingular AT&T have merged to create the new AT&T and Alcatel and Lucent have merged to create Alcatel-Lucent.)

As to John’s comment that the AT&T solution is proprietary, we would agree because we think that every IMS-based solution will require some level of proprietary work as each carrier’s network and back office if different. And one of the benefits of IMS is that it is built to provide a common framework to accommodate diverse legacy and future network requirements.

Regarding John’s concern about the potential for patent disputes, we suppose that especially with all the new technological developments and the history of litigation to protect intellectual property, AT&T could face a dispute. But we also know AT&T has its own track record of avoiding patent infringements and with a large legal staff in its ranks, we remained unconcerned about the possible outcome.

Next time, we’ll hear from Prabhat who responded via the newsletter’s comment mechanism. By the way, if you’d ever like to provide feedback, please feel free to send us an e-mail (by clicking on our names underlined below) or comment via the comment box below (click on the word “react”).

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Larry Hettick is a principal analyst at Current Analysis.