The Motor Racing Network (MRN) is the radio broadcasting operation of NASCAR. It broadcasts coverage of most major NASCAR races at the top three levels of NASCAR: the NEXTEL Cup, the Busch Series and the Craftsman Truck Series. The exception to these are races held at tracks controlled by Speedway Motorsports, Inc., which operates their own radio network called the Performance Racing Network, and the Allstate 400 at the Brickyard, which is broadcast by Indianapolis Motor Speedway's own radio network. All Craftsman Truck races are broadcast on MRN regardless of track ownership. The Nextel Open and Nextel All-Star Challenge are also broadcast on MRN despite being held at Lowe's Motor Speedway, an SMI-owned track. MRN promotes itself as the "voice of NASCAR".