Sprint has announced its Sprint 3G/4G USB Modem U300, the first device to operate on both 3G and 4G wireless broadband networks. The modem is designed to operate on Sprint's WiMAX network and offers download speeds of 2-4 Mbps. Download speeds on the Sprint 3G network run from 600 Kbps to 1.4 Mbps.

The modem is built for Sprint by Franklin Wireless and sells for $149.99 with a 2-year agreement and a $50 mail-in rebate. Sprint subscribers will be able to purchase the modem starting on December 21st via the Sprint direct business sales force.

The biggest catch for the modem is that only customers in Baltimore can currently access Sprint's 4G network. Sprint says it will be rolling its 4G network out to more areas in 2009. The odds of the network seeing a big roll out next year are slim and will be limited to large urban areas.

Via Sprint