Clearwire has stopped offering postpaid plans to new customers and will no longer sell dual-mode WiMAX/3G devices that use Sprint’s CDMA network.

Clearwire no longer offers its $45 postpaid plans. It has stripped down its offerings to just two $50 prepaid WiMAX-only plans: one for its mobile hotspot and USB modems, and one for its in-home modem.

The changes only apply to new subscribers and don’t affect existing customers.

“We are making the changes in an effort to simplify our product offerings and focus on our core 4G network,” company spokesman Mike DiGioa said. “The dual-mode product made up a very small part of our total Clear customer base, and the dual-mode products for the Clearwire network are still available from other providers, including Sprint.”

The company decided to move forward with the changes after conducting trials of the new plans in Georgia earlier this year. The shift away from postpaid also comes after Clearwire canned its Rover prepaid brand last spring. The brand was targeted at young adults.

News of the new plans leaked out yesterday after DSL Reports took note of comments on user forums and a Clearwire retailer website.

The changes also come on the heels of Sprint’s decision to phase out its use of Clearwire’s WiMAX network. Both companies are moving ahead with their own LTE networks, though Clearwire needs to raise $600 million before it can begin rolling out the new gear. Sprint plans to use Clearwire’s LTE service to add additional capacity to its own LTE network.