Under the brand name Direct Connect, Nextel's PTT is widely used by workers who spend most of their time in the field, such as construction crews, firefighters and appliance repairers.
A carpenter on a big job site can hit the PTT button to ask, "Who has more 16-penny nails?" Seven other carpenters would hear the message, and the one with the most extra nails could reply.
Nextel is relatively small, with 11.7 million subscribers, and has never been particularly successful at selling its service to consumers - in part because of its rates.
Verizon Wireless is the largest wireless carrier in the nation, with 34.6 million customers and more skill at marketing new services. For now, it is aiming PTT at businesses willing to pay premium prices.
The company charges $20 a month on top of existing rates; the least expensive PTT plan is $59.99 a month and, except for PTT, is identical to the regular $39.99 plan providing 400 anytime minutes along with unlimited nights and weekends.
Anyone signing up for PTT from Verizon Wireless before the end of this year gets unlimited one-to-one and group PTT calling for as long as he or she maintains the account; regular phone calls are charged the same as with non-PTT phones.
After Jan. 1, customers signing up for PTT will still get unlimited one-to-one calls, but group PTT calls will cost the originator 15 cents per person contacted. In other words, a group call you start with three other people would cost 45 cents a minute; the people on the other end still pay nothing.
I'm not sure if PTT is a feature I'd use regularly, and I don't know how fast my friends or co-workers will acquire PTT-ready phones. What's more, it's likely to be at least several years before PTT works between different wireless carriers.
But I'm also convinced that PTT isn't just for business; I can easily see PTT becoming a popular way for people to reach out to family and friends.