signalling ATM adaption layer (SAAL)
The SAAL layer resides between the ATM layer and the Q.2931 function. SignallingATM Adaption Layer (SAAL) provides reliable transmission of Q.2931 messages between so-called Q.2931 instances, such as ATM switches and hosts, via the ATM layer. The Service Specific Connection Oriented Protocol ( SSCOP) resides on the SAAL layer.