'Secret' hybrid push-to-talk and Wi-Fi mobiles on the way

Mobile carriers are creating "push-to-talk" services that travel over Wi-Fi networks, federal regulators say - a move that could expand the one-push cell phone calls to VoIP systems.

The technology development was disclosed by the Federal Communications Commission in a notice of proposed rulemaking on the Communications Assistance for Law Enforcement Act (CALEA), a 160-page document released last week that discusses how to regulate internet services.

In the same document, the FCC reiterated its belief that push-to-talk calls are subject to federal wiretapping requirements.

Push-to-talk technology enables callers to connect to other mobile phones with just the push of a single button, similar to a walkie-talkie. Only one person can talk at a time, and there is no need to dial a number. In the decade since the technology was developed by Nextel Communications and Motorola, push-to-talk services have only been available over cellular networks.

Wi-Fi networks are typically connected to the public Internet. Push-to-talk calls over Wi-Fi would likely be able to reach homes and offices that have so-called voice over Internet Protocol (VoIP) telephones. About 600,000 homes worldwide use internet-based phone services now but that's expected to expand significantly over the next few years.

The FCC did not state which US carriers are working on the hybrid technology. One likely candidate is Verizon Communications, the landline company that's also part owner of Verizon Wireless, which sells a push-to-talk service. In the past, Verizon Communications executives have made references to expanding push-to-talk services to traditional phones.

Representatives of the two Verizon companies declined to comment. Nextel Communications and Sprint, the other two US carriers offering push-to-talk service, also had no comment.

It's unlikely that any Wi-Fi push-to-talk services, which at their core are based on VoIP technology, will launch any time soon. If they do get up and running, they could prove to be a revenue generator for Wi-Fi hot-spot operators, which could charge users a fee to use their networks and split the revenues with cellular providers.

Even though it's clearly early on in the development cycle of the technology, the FCC is already pointing out how Wi-Fi push-to-talk services might create regulatory headaches, especially for law enforcement.

The systems being developed would not interconnect with the public switched telephone network and would therefore not be subject to rules compelling wireless carriers to cooperate with federal wiretapping requests, the FCC said.

Ben Charny writes for CNET News.com