T-Mobile is offering a new way to connect your PC to its growing 3G network.

On Nov. 11 the carrier introduced a USB-style PC modem called WebConnect Jet, which is being offered free with a two-year service contract. Users can connect to 3G networks in the U.S and 2G EDGE networks abroad.

Feeling festive — with a holiday smartphone lineup in place — T-Mobile is offering a holiday promotion, through Jan. 13, on the plans users can pair the modem with. Its 200MB-per-month plan is now $29.99 (a savings of $5) and the 5GB-per-month plan has dropped by 10 bucks, down to $49.99.

Just as mobile phone coverage and speeds are again being made a first priority, T-Mobile is also announcing it’s been aggressively building out, and speeding up, its network.

In March, it effectively doubled its 3G coverage, and it’s on track to cover just over 200 million people by the end of the year.

“At the same time, we’re also improving the radio interface to that network, so we’ll be the first national carrier to implement HSPA — high-speed packet access — at 7.2 Mbps across that entire network,” Jeremy Korst, director of broadband products and services at T-Mobile, told eWEEK.

“In addition to that, we’ve also launched a trial network for HSPA+, which is a 3.5G network technology that delivers theoretical peak downlinks of 21Mbps in our Philadelphia market,” Korst continued. “We’re actively testing that with some devices, and will be over the next several months, and then aggressively launching that technology in many of our large metropolitan markets throughout the course of next year. So we’ll be the first to have HSPA+ coverage in a broad-scale network deployment through next year.”

Korst said some initial tests of HSPA+ have shown faster speeds than those claimed by early 4G providers of WiMAX and LTE, and that a “thriving device ecosystem” for HSPA+ has enabled T-Mobile to bring those devices to market before 4G’s arrival.

“The 3.5G devices are backward compatible, so the devices we’re selling today will get faster data speeds on our network tomorrow, with no need to upgrade,” Korst said.

T-Mobile is focusing its efforts on not only enterprise users, but small businesses users and consumers.

WebConnect Jet isn’t “focused on the more technologically intensive applications, like it would have been a few years ago,” Korst said. “It’s all about ease of use, simplicity, plug and play and a Connection Manager that easily connects you to the best network. So that next set of users, whether consumer or SMB, can start to adopt more and more.”

EDITOR'S NOTE: The myTouch and Cliq smartphones are HSPA compatible, not HSPA+. Also, the 200MB plan has been temporarily reduced by $5, while the 5GB plan has been reduced by $10.