Editing GPRS core network (section)

==GPRS tunnelling protocol (GTP)==
{{main|GPRS Tunnelling Protocol}}
''GPRS Tunnelling Protocol'' is the defining [[Internet Protocol|IP]]-based [[Communications protocol|protocol]] of the GPRS core network.  Primarily it is the protocol which allows end users of a GSM or WCDMA network to move from place to place while continuing to connect to the Internet as if from one location at the [[#Gateway GPRS support node (GGSN)|Gateway GPRS support node (GGSN)]].  It does this by carrying the subscriber's data from the subscriber's current [[#Serving GPRS support node (SGSN)|serving GPRS support node (SGSN)]] to the GGSN which is handling the subscriber's session.  Three forms of GTP are used by the GPRS core network.

;GTP-U: for transfer of user data in separated tunnels for each [[#PDP context|Packet Data Protocol (PDP) context]]
;GTP-C: for control reasons including:
:* setup and deletion of PDP contexts;
:* verification of GSN reachability;
:* updates; e.g., as subscribers move from one SGSN to another.
;GTP' (pronounced "GTP Prime"): for transfer of charging data to the Charging Gateway Function.