I have, until now, been under the impression that the term “Push to Talk” is a trademark of either Motorola or of Nextel, and that using it in a more general sense was generally asking for trouble.
Then, today, I spotted a Verizon ad advertizing their “Push to Talk phone.” The capitalization is theirs, which gives it almost a trademarked feel. However, there isn’t any indication of trademark ownership anywhere in the ad (aside from the places you’d expect it — next to the Verizon logo, for example).
So, I checked with the USPTO (which doesn’t let you bookmark into trademark searches, but you can go here, click on “trademark search,” then “basic search” and type in “Push to Talk”), and apparently, Nextel (who had previously registered the term “Push to Talk”) abandoned its use of the trademark in November of 2004.
That said, the term “Push to Talk Worldwide” has been registered as a service mark in a VoIP context by an individual (not a company). Also, Motorola is still maintaining a trademark on the term “P2T,” although that registration explicitly says that they don’t claim “PTT” as a trademark. “PTT” used to be registered by a company I’m not familiar with, but its use was abandoned in 2000.
So, there you go. For the time being, it appears that you can use “Push to Talk” and “PTT” without any fear of the lawyers coming after you1. In fact, they’ve probably become common enough that trademarking them would be pretty much impossible.
“PoC” doesn’t appear to be registered in the U.S.; although, any such registration would probably be difficult due to nontrivial overlap with the trandmarked name of “POC,” owned by Physical Optics Corporation, which makes data switching equipment for telecom and datacom networks.
1 Anyone taking legal advice from a blog deserves any trouble they get.