Network Service Access Point Identifier

A Network (Layer) Service Access Point Identifier (NSAPI), is an identifier used in GPRS (cellular data) networks.

It is used to identify a Packet Data Protocol (PDP) context (a unique data session) in the Mobile Station (MS) and in the Serving GPRS Support Node (SGSN). It is dynamically selected by the MS (however, the MS should ensure that the selected NSAPI is not currently being used by another session management entity in the MS). When the MS requests a PDP context, it selects an NSAPI that it sends to the SGSN with the request.