MAP (Mobile Application Part)

The Mobile Application Part is the SS7 application protocol used in 2G and 3G networks for subscriber-related signalling: location updates, roaming, SMS delivery, supplementary services, and authentication vector retrieval from the HLR. MAP messages carry IMSIs, MSISDNs, and routing data in cleartext and assume the underlying SS7 network is trusted. As a result, MAP is the protocol abused by most well-known SS7 attacks (location tracking via SRI-SM, call and SMS interception via UpdateLocation), and filtering MAP operation codes is the central job of an SS7 firewall.

Categories: Core NetworkSignalingRoaming and Interconnect

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

Related terms

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