Sprint Nextel and Verizon Wireless already offer. With Cingular now onboard, three of the four major cell phone operators in the United States offer the feature. The service, which allows a cell phones to act like a walkie-talkie, was first offered by Nextel in the U.S.
Cingular, which is jointly owned by BellSouth and AT&T, is charging subscribers $9.95 per month for unlimited use of the walkie-talkie service. Family plans cost $19.99. Currently, it's only available on two phones: the Samsung D-357 and the LG F7200.
The new service is being powered by technology from Kodiak Networks. Several other wireless providers also use Kodiak's technology, including Orange in Europe and, in the U.S., Alltel and Verizon's Mobile Virtual Network Operator, called AMP'd.
With Cingular's push-to-talk service, people can transfer directly to a regular call. They can also use a feature that lets them know if the person they are trying to reach is available. The service lets people conference in up to 20 callers on the same conversation.