A mobile phone offering cellular and VoIP connections in one has been announced.

UTStarcom's new GF200 cell phone, previewed last week at the Consumer Electronics Show in Las Vegas, combines GSM and VoIP over WiFi. It should be available in the spring, the company said, while refusing to discuss price.

WiFi VoIP phones aren't anything new. But they are more cordless phone replacements for home use than cell phone competitors, said Michael Tribolet, executive vice president of Vonage, because people probably don't want to carry two phones just to have both cell and VOIP access.

The GF200 looks like just another cell phone - which is just the point. It is intended to be a replacemeny by offering both in one handset.

Connecting to both GSM and WiFi networks at the same time, and sending a call over either one is not simple. But it holds huge possibilities. The ability to configure most VoIP services to forward calls to another number when the VoIP number is unavailable will let people use cheaper Internet access to receive and make calls when in range of a WiFi network, and automatically divert to the cellular service when not.

Don't expect to be able to get a GF200 with a new mobile phone pricing plan any time soon though, said Howard Frisch, director of handset production at UTStarcom. It's highly unlikely that existing mobile companies will want anything to do with a phone that could slash their revenue, he pointed out.

The situation is worse in the US, so Europe will probably be the first market to see any real distribution, Frisch said. In Europe, the approach of buying a phones and then adding a particular company's SIM card is more widespread than in the US.

There are also restrictions on use of the phone over WiFi. You can only use the phone with a VoIP company that will give you the SIP credentials you'll need to connect to their network, Frisch warned. Larger VoIP companies like Vonage won't release your SIP credentials, he said.