Glossary

MSISDN

An MSISDN (Mobile Station International Subscriber Directory Number) is the full international telephone number that identifies a mobile subscription on a GSM/3GPP network — in everyday terms, the mobile phone number people dial to reach you.

Updated 26 Sept 2026By PhoneBorn TeamEditorial policy

Structure

An MSISDN follows the ITU-T E.164 numbering plan and has three parts:

CC — Country Code: 1–3 digits (1 for the US and Canada, 44 for the UK, 91 for India).
NDC — National Destination Code: identifies an operator or a numbering range within the country (in some countries this is less meaningful after number portability).
SN — Subscriber Number: identifies the individual subscription.

Example: in +44 7700 900123, the CC is 44, the NDC is 7700 and the SN is 900123. The total may not exceed 15 digits, and it is written without the national trunk prefix (the leading 0 used in domestic dialling). The dialled form with a plus sign is covered under E.164.

MSISDN vs IMSI vs ICCID

Identifier	What it identifies	Where it lives	Public?
MSISDN	The subscription's phone number	Network (HLR/HSS)	Yes — you share it
IMSI	The subscriber identity on the SIM	SIM and network	No
ICCID	The physical or embedded SIM card	Printed on SIM / eSIM profile	Rarely

The network maps MSISDN to IMSI. That mapping is why an operator can move your number to a new SIM — legitimately when you replace a lost card, or fraudulently in a SIM swap. It also explains why an eSIM can carry the same number as a physical SIM.

Why it matters for verification

APIs and verification systems often use "MSISDN" as the field name for the phone number. When a service performs an HLR lookup, it queries by MSISDN. If you integrate SMS through an API, store numbers as full MSISDNs in E.164 form to avoid delivery failures caused by missing country codes. PhoneBorn's phone number API returns numbers in international format for this reason.

Put it into practice

MSISDN: FAQ

Is the MSISDN stored on the SIM card?

Not reliably. The SIM stores the IMSI; the MSISDN is assigned by the network and linked to the IMSI in the operator's database. Some SIMs have an optional field showing the number, but it is often empty or outdated.

Does an MSISDN include the plus sign?

Strictly, the MSISDN is the digits only (country code, national destination code and subscriber number). The plus sign is a dialling prefix used when writing the number in E.164 international format.