Sprint has begun private-labeling its Clearwire subsidiary’s 4G WiMAX service in Austin and San Antonio, Texas.

The two Texas cities join a growing list of Sprint 4G communities that includes Atlanta; Chicago; Las Vegas; Philadelphia; Portland, Ore.; Bellingham, Wash.; Boise, Idaho; Milledgeville, Ga.; and several cities in North Carolina . Sprint also plans to deploy Sprint 4G service in these additional markets in 2009: Honolulu and Maui, Hawaii; Salem, Ore.; and Seattle.

In 2010, Sprint expects to launch service in multiple markets, including Boston, Houston, New York, San Francisco and Washington, D.C.

Separately, Sprint paid down the last $1 billion of $4.5 billion borrowed through a revolving credit facility. With the payment, Sprint said it no longer has an outstanding balance.

The company said that at the end of the third quarter of 2009, it had $5.9 billion in cash, cash equivalents and short-term investments, and $1.6 billion in borrowing capacity available under its revolving bank credit facility, for total liquidity of $7.5 billion.