Number Portability (Mobile / Local Number Portability)

Also known as: MNP, LNP, Mobile Number Portability

Number portability is the regulatory capability that lets subscribers keep their phone number when changing operator. Networks resolve ported numbers via a national portability database or All Call Query, and the routing information is carried in SS7 (Release-to-Pivot, IN triggers) or in Diameter/SIP for LTE/VoLTE. From a security perspective, portability requests are a high-value target for SIM-swap-like account takeover and require strong subscriber authentication.

Categories: SignalingIdentity and Subscriber

Number Portability in context

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.

Subscriber identifiers (IMSI, SUPI, MSISDN, IMEI) anchor authentication, charging and lawful interception. Any protocol that leaks a permanent identifier is treated as a privacy defect, which is why 5G introduced SUCI concealment on the air interface.

To place Number Portability in the wider telecom-security picture, review AAA, Any-Time Interrogation (ATI), Behavioral Signaling Detection, BTS Impersonation (Fake BTS), CAP and Cleartext (Plain Text) — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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