The CDMA working Group Interoperability Specification (IOS) defines the messaging interface between a Code Division Multiple Access (CDMA) Base Station (BS) and a Mobile service Switching Center (MSC). This interface uses the services provided by connection-oriented SCCP for its transport layer. The Accelero™ IOS API allows for the rapid development of the MSC-BSC interface.
 
The purpose of IOS CDMA is to provide the standard A1-Interface to a truly open interface to a Mobile Service Switching Center (MSC) of a CDMA wireless telecommunication network with one or more Base Stations (BS). The MSC-BS interface provides telecommunications service access between a BS and an MSC. The IOS CDMA also designates the operational division of responsibility between the BS and the MSC and permits the separate evolution of MSC and BS technology.
 
IOS CDMA signaling for the A1 interface relies on the SCCP to setup the connection control. The IOS CDMA protocol uses the Class-2 basic connection-oriented services of SCCP.