Cheeky Cingular took the wraps off its Push To Talk service today, inviting subscribers to join the "largest Push To Talk network" in the US.

That honor belongs to Sprint-Nextel, of course, it's a feature that Nextel pioneered using Motorola's IDEN network, birthplace of the chirp that announces an incoming message. Cingular is merely the largest network in the US, a shade ahead of Verizon. Nevertheless Cingular becomes the largest GSM operator in the world to add the feature, so it's a genuine milestone.

Cingular will charge $9.99 for unlimited use, or $19.99 for all the phones covered by a family talk plan.

GSM operators have been leery about introducing PTT, as amongst other things, it's a natural and much more user friendly replacement for text messaging. You just push a button, and a "voicemail" is delivered to the recipient. Since text messaging forms the bulk of their data revenues, carriers have been reluctant to compromise the cash cow.

Cingular desperately needs more phones to support the service: it only works with one model right now, the LG F7200 slider, with the higher-specced Samsung D357 flip "coming soon". While all of Nokia's forthcoming E series support PTT, Cingular surely wants more in alow end that appeals more to the younger demographic.

More details in Cingular's FAQ.®