Listen to the "KREF Sports Radio Network" radio station live. The "KREF Sports Radio Network" studio is located in Norman, OK. Callsign: KREF (1400 AM) | K257DA (99.3 FM). Broadcasting region: Oklahoma City Metroplex. Start of broadcasting: September 1, 1949. Program format: Sports. Target audience: 18-54 years old. Audience Reach: 1,425,695.