Motorola Inc., after nearly a year of vague pronouncements, unveiled Tuesday an ambitious music radio service for cell phones that also plays over car and home stereos.

Motorola iRadio, featuring 435 channels, would be sold by wireless service providers to their subscribers for between $7 and $10 per month — a few dollars cheaper than the satellite radio networks that would be among the phone-based service's immediate rivals.

No wireless carriers have signed on yet to carry iRadio, which may also be adapted for non-Motorola phones if carriers request it, company officials said.

In some ways, iRadio more closely resembles a vast "podcast" network rather than a traditional radio broadcast.

Motorola expects about 90 percent of its content to be loaded on phones from the Internet over a personal computer, rather than broadcast over the air, in this case a cellular network.

That would mean less of a strain on the limited capacity wireless operators have for mobile calls, e-mail and Internet services.

iRadio marks a rare foray into consumer services for Motorola, one of the world's top producers of mobile devices and network equipment.

While the service may help sell Motorola phones, headsets and other wireless gear, the company also views the system as a new business model for radio, much as Apple Computer Inc. broke the mold for selling music with its iTunes online store.

Not surprisingly, Motorola sees the phone as the focal point of this new model, not only serving as a portable music player but emerging as a roving conduit and repository for music that can feed a home or car stereo.

To enable this vision, Motorola has developed a Bluetooth wireless adapter for car radios so that a cell phone can broadcast its content over a car's speakers. Motorola said the device and installation is expected to cost $200 or less. Motorola is also selling a Bluetooth adapter to connect phones with home stereos.

The commercial-free network will feature channels created by Motorola through its partnerships with music labels, as well as stations from other broadcasters.

In October, Motorola signed a licensing deal with the Universal Music unit of General Electric Co., and an agreement with Warner Music Group Corp. is slated to be announced this week. Some of the iRadio stations will be devoted to a single artist from those labels.

For now, about a half dozen Motorola handsets due on the market this year through undisclosed carriers are compatible with iRadio.

One is the next edition of the ROKR, a phone that's generated only tepid sales through Cingular Wireless despite its status as the first handset to play iTunes.