Sprint Nextel is on a quest of writing its name in the book of wireless history, and today’s announcement is a clear sign that its dream is about to come true. The company revealed plans for a 3G/4G dual-mode device that will be able to operate on both wireless networks as of December 21.

The announcement came just as the 4G network continues expanding throughout the country. Sprint has already launched 4G in Baltimore and said the service will expand to other markets as well, starting next year.

The Sprint 3G/4G USB Modem U300 combines both 3G capabilities, which are basically a must these days, and 4G wiMAX capabilities, which represent the future of broadband access.

Dan Hesse, Sprint CEO, said this reflects the company’s goal to become 4G leader and bring the wireless Internet to life. Furthermore, it will allow customers to connect to the Internet virtually anywhere there is a 3G and 4G network.

What this means for consumers is that they will be able to do everything faster, including downloading a song in several seconds, or a movie in less than an hour, while walking around. This is of course thanks to the 4G technology, which is far superior in terms of speed to 3G.

The device is manufactured by Franklin Wireless, and connects to a standard USB port. Sprint said it will cost $149.99 with a two-year subscription agreement, after a $50 mail-in-rebate. Furthermore, for $79.99, customers will have access to 3G and 4G mobile broadband services.