U.S. WiMAX carrier Clearwire is running a trial of mobile VoIP phones in Portland, Oregon and should be launching mobile voice services in 2010. The company has been discussing how it can work with its cable partners/investors to offer mobile voice services and handsets.

Under the deployment plan, mobile VoIP handsets will be tested out this year with voice being incorporated into the product line in 2010. A company executive said it is testing the usage model, integration with the home phone and WiMAX network, and “how you hand off to a cellular network” like Sprint’s.

The VoIP-over-WiMAX technology is vitally important to cable carriers invested in Clearwire, as it offers them mobile options for bundling to more effectively compete with AT&T and Verizon. Clearwire investors Comcast, Time Warner Cable and Bright House Networks have the option to buy WiMAX access services from Clearwire on a wholesale basis.

MSOs could conceivably offer wireless phone services as a simple extension of their existing wireline VoIP offerings; it would just be matter of routing the packets from one IP network (cable broadband) to another one (WiMax broadband).

The effect of Whitespace regional broadband Internet on the WiMax business model is unknown at this time. See more about whitespace and the use of analog television frequencies for regional wireless Internet coverage of up to 75 miles.