The packet data protocol (PDP; e.g., IP, X.25, FrameRelay) context is a data
structure present on both the Serving GPRS Support Node (SGSN) and
the Gateway GPRS Support Node (GGSN) which contains the subscribers
session information when the subscriber has an active session. When a mobile
wants to use GPRS, it must first attach and then activate a PDP context.
This allocates a PDP context data structure in the SGSN that the subscriber is
currently visiting and the GGSN serving the subscribers access point. The data
recorded includes