The CDMA phone demonstrators were using at today's Sprint Ahead technology event was an unnamed prototype Sanyo clamshell with a body like a chunky Katana and a rubberized back - see the pictures after the jump. And the demo was pretty simple. You press the button, the push-to-talk connects, you're talking.

Of course, getting there wasn't simple. Everybody has tried doing push-to-talk over cellular - Verizon, Cingular, even Sprint themselves. But what they got was usually more like push-to-wait-to-talk, stuck with much higher latencies than the slow-but-quick Nextel network.

More after the jump ...

If the demo I saw today was for real, those days may be coming to an end. "Nextel is not a service, it's an application," said Tim Kelly, Sprint's chief marketing officer. By early 2008, Sprint will start rolling out CDMA EVDO Rev A phones with a push-to-talk button on them that talk to Nextel phones, and talk like Nextel phones, he said. Existing users switching over can port their existing Direct Connect numbers or simply use their phone numbers.

(For non-Nextellers, Nextel phones have two phone numbers: a normal human one and a special magic Nextel one that looks like 12*345*678, for pushing-to-talk.)

"We are going to significantly expand the range of handsets, and we're going to open up a lot of appealing handsets" for push-to-talk, Kelly said.

The new service will initially only work in the US, though you'll be able to make outgoing chirps to foreign Nextel users. Sprint's working on getting roaming agreements for the service so it works in Canada and Mexico.

So why doesn't this suck? Iyad Tarazi, Sprint's vice president of network development, said the company has created a "special version" of EVDO Rev A in cooperation with Qualcomm, who also developed their new push-to-talk software, QChat. The "special version" enables low-bandwidth connections at very low latency, which is what you need for good push-to-talk.

All of Sprint's major handset vendors are working on phones for the new service, Tarizi said. So don't assume that the Sanyo phone I'm showing below is absolutely, positively the first phone. Just take it as inspiration.