The event Monday night was Sprint Nextel's launch of its 4G wireless service for Internet and streaming video at the Sheraton Philadelphia City Center Hotel.

The same 4G service will be launched today by Comcast Corp. Three cars will zip around town with demonstration laptops. A "rip-away" living room outside the company's headquarters in Center City will show customers how they can take high-speed Internet service outdoors.

And tomorrow, Clearwire Corp. - the third player in this trifecta of product launches - will announce its offering of 4G wireless Internet service with the Clear brand with events at JFK Plaza.

Although they are announcing separately with their own marketing hubbub, the three companies are using the same telecommunications infrastructure and spectrum, and are basically offering the same service.

The term 4G refers to the next generation of wireless services, with speeds similar to those of a cable modem.

The 4G network was built by Clearwire, based in the Seattle area. Sprint and Comcast invested in Clearwire to beat Verizon Communications Corp. and AT&T Inc. to the fast-wireless market.

Philadelphia is among the first big metropolitan markets with the 4G service - along with Atlanta, Chicago, Dallas, Las Vegas, and Portland, Ore.

Initial 4G coverage in the Philadelphia area will be Center City and the inner ring of suburbs, the companies say.

With the limited 4G coverage area, customers could use 4G service and then default to Sprint's slower 3G network outside 4G coverages - for an extra fee.

Comcast is selling 4G with its wired Internet service for homes as a product bundle. The wireless service, with the traditional wired service, costs $49.99 a month for 12 months.

Clearwire's lowest prices are $25 a month for wireless home Internet and $35 a month for mobile Internet, a company spokesman said. Both packages require a wireless modem, which is an additional rental or purchase cost.

Sprint is offering the 4G service for a promotional price of $59.99 a month for customers who sign a two-year contract. The promotional price ends Jan. 10.