Sprint Nextel Corp. (NYSE: S) says that it now has four new Mobile WiMax markets "in development" in addition to Baltimore, Chicago, and Washington.

A spokesman for the operator confirms that it is now plotting WiMax deployments in Boston, Dallas-Fort Worth, Philadelphia, and Providence, R.I. Sprint spokesman, John Polivka, says that the carrier isn't yet detailing deployment schedules for the cities but does allow that "it is unlikely to be this year."

Sprint says that it is on track to go commercial with its first WiMax market in Baltimore this September. (See Sprint: More on B'More.) Chicago and Washington are slated to follow "some time in the fourth quarter," says Polivka.

In fact, Sprint CTO Barry West tells the Sidecut Reports blog that the carrier is now ahead of its planned schedule for XOHM WiMax, having just switched on its 1,000th WiMax base station. Yesterday, the carrier unveiled one of its first major services for the nascent network, localized information mapping for mobile users. (See Sprint Plots WiMax-Powered Location Services.)

All of this network activity should eventually get swept into the "new Clearwire" WiMax venture network, which combines Sprint's and Clearwire's WiMax assets. Kirkland, Wash.-based Clearwire is expecting to switch on its first WiMax market in Portland, Ore. (See Clearwire: We're Ready for Primetime.)

Much of Clearwire's deployments, however, could hinge on the "new Clearwire" deal closing as expected in the fourth quarter. The operator has repeatedly insisted that the WiMax merger and associated $3.2 billion funding is still on track to close by the end of the year. (See The WiMax State of Play in the USA.)

— Dan Jones, Site Editor, Unstrung