Sprint’s iDEN push-to-talk service, which is in the process of being phased out, will be replaced by a larger CDMA system with faster data speeds and better in-building coverage.

Sprint’s new CDMA-based Direct Connect push-to-talk service will launch in the fourth quarter. Its footprint will be more than double that of the current iDEN system, covering 2.7 million square miles and 309 million people with the inclusion of 1xrtt and roaming coverage.

Sprint’s current iDEN network covers 908,370 square miles and 278 million people. Sprint plans to phase out all iDEN cell sites by 2013 as part of its $5 billion network overhaul plan.

“We’ve seen steadily increasing demand for faster data speeds, better and broader coverage, and more applications on push-to-talk devices,” said Paget Alves, president of Sprint Business, in a statement. “Sprint Direct Connect is designed to solve for all three.”

Alves says Direct Connect will offer sub-second set up time for push-to-talk calls in Sprint CDMA RevA coverage areas. Sub-second call set up is expected to expand across the country as Sprint completes its network upgrade plans.

Sprint has compiled a lineup of ruggedized devices from Motorola Mobility and Kyocera to run on the new service. The planned portfolio will include a camera flip phone and an Android-based smartphone with a touchscreen and qwerty keyboard. Sprint will expand its line of Direct Connect devices next year.

The devices will be able to handle group push-to-talk for up to 200 participants, land mobile radio (LMR) interoperability, and availability notifications. Sprint will add additional capabilities to the Direct Connect service in early 2012, including international push-to-talk.

Sprint said it is already working to migrate its existing push-to-talk customers to the new CDMA service. The company has also launched an application developer program, Sprint Gets Rugged, to create apps using the push-to-talk capabilities of the Direct Connect service.