With its UMTS networks scheduled to launch in a matter of months, Cingular is adding service to the high-speed data networks it already has, announcing today it is adding a Research in Motion Blackberry handset to its growing list of EDGE devices.

The Blackberry 8700c is the first the RIM device to support the last evolution of GSM data technology before, and Cingular has signed an exclusive distribution deal for the handset in the U.S. With speeds of around 100 kb/s, the technology has taken a back seat to 3G technologies—while providing capacity improvements over CDMA 1X and GPRS it doesn’t approach the capacity of UMTS or EV-DO networks.

Since 2003, however, Cingular has been rolling out a nationwide EDGE overlay, and despite delays in getting EGDE devices to market now has several PC cards and handsets supporting the technology launched over the network. More significantly though, Cingular is looking toward EDGE to play a critical roll in supporting its UMTS rollout, allowing customers to roam off its 3G high-speed downlink packet access (HSDPA) onto what will would be the most robust 2.5G network in the country.