Sprint has unveiled a wireless modem designed for 3G and 4G networks. The USB-powered U300 device is the first in the US market to run on both 3G and WiMax wireless networks.

The company hopes that the device, due on 21 December, will appeal to notebook users who would like to try the new 4G networks without giving up support for the older 3G wireless broadband systems.

Sprint's WiMax domain is currently limited to a single network in Baltimore, but the firm hopes to add a nationwide WiMax operation as its merger with Clearwire continues to progress.

"Sprint intends to be the leader in 4G and bring the wireless internet to life," said Sprint chief executive Dan Hesse.

"This first-of-its-kind device allows our customers to take the internet with them wherever they go by gaining enhanced speed and capability in 4G markets and the nationwide coverage of our 3G network across the rest of the country."

The device will be priced at $149 (£96) with a $50 (£32) mail-in rebate. Users will be required to sign a two-year data contract at $79.99 (£51) per month.