GTP (GPRS Tunneling Protocol)

The GPRS Tunnelling Protocol carries user data and control signalling between core network elements in 2.5G GPRS, 3G UMTS, 4G LTE, and 5G non-standalone deployments. It exists in three flavours: GTP-C for control-plane signalling between SGSN/MME/SGW/PGW, GTP-U for user-plane data tunnelling, and GTP' for charging. GTP was designed to run on private GRX/IPX backbones and has weak built-in authentication, making it a frequent target for IMSI disclosure, session hijacking, denial of service, and bearer redirection. Operators protect it with dedicated GTP firewalls and strict peer validation.

Categories: Core NetworkSignalingRoaming and Interconnect

GTP in context

The mobile core carries subscriber sessions, mobility and policy. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF.

Signaling protocols carry the control-plane messages that set up calls, register subscribers and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA as top-tier telecom risk.

To place GTP in the wider telecom-security picture, review FS.07, FS.19, GGSN, GTP Firewall, HLR and HSS — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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