DS0A

DS0A is the interface most commonly used for SS7 networks in the US. It is a 56/64kbps channel typically located in a DS1 or larger facility. The DS0A electrical interface usually only exists inside a central office environment, and only exists for the sole purpose of connecting into a channel bank to be multiplexed onto a higher facility.

Sources

• Cisco SS7 Fundamentals

Russell, Travis. Signaling System # 7 Mcgraw-Hill Telecommunications