I believe the number is through Google Voice.

The call to me was from:

http://www.sw-credit.com/

PHONE: 972.300.1700  |  TOLL FREE: 800.637.7439  |  FAX: 972.300.1701
POSTAL ADDRESS: 4120 International Pkwy #1100, Carrollton, TX 75007
    
© 2009 Southwest Credit Systems, L.P.

Southwest Credit is a nationally recognized debt collector.

Regarding another person's debt.

Unfortunately, other people call me using Google Voice.

Scumbag debt collectors.