Sprint on Wednesday unveiled a dual-mode modem that will operate on both its 3G data network and Clearwire’s higher-speed WiMAX wireless broadband network.

That will allow mobile users the choice of either 3G speed that tops out at perhaps 1.5 Mbps or WiMAX speed that can reach around 3 Mbps, where WiMAX is available.

Sprint, the third-largest mobile carrier in the United States, is hoping to rejuvenate its sagging mobile business by being the first carrier to support a 3G and a 4G wireless broadband technology in the same device.

“This first-of-its-kind device allows our customers to take the Internet with them essentially 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,” Sprint CEO Dan Hesse said in a statement.

But that so-called first-mover advantage could be too little, too late for Sprint because the target market for wireless broadband modems is small, and LTE, a competitive technology, is looming on the horizon,  analyst Shahid Khan said.

“People who would be interested in this modem are business people on the go and to them coverage is much more important than speed, and both Verizon and AT&T have extensive nationwide 3G coverage,” said Mr. Khan, senior partner at IBB Consulting.

Business users are more interested in email than they are in high-bandwidth services such as games and video, so the higher speeds available on WiMAX will not get Sprint the market traction it is seeking, he said.

The specifications for LTE, a technology that will compete with mobile WiMAX, are still being hashed out, but WiMAX has a two-year window of opportunity before LTE emerges as a commercial technology.

Sprint, which merged its WiMAX business with Clearwire, its biggest WiMAX rival, has to move quickly to carve out a sustainable role in the mobile market or face extinction when AT&T and Verizon begin rolling out their LTE networks. (Tech Consortium Bids $14.5B on WiMAX)

One option for Sprint is to get Dell and other PC-makers to integrate WiMAX modem technology on the PC motherboard, which will open another base of users to WiMAX.

“A lot of people will buy a laptop and use whichever service comes built-in,” Mr. Khan said.