MSISDN
Mobile Station International Subscriber Directory Number or an MSISDN is a number uniquely identifying a subscription in a Global System for Mobile communications or a Universal Mobile Telecommunications System mobile network. It is the mapping of the telephone number to the subscriber identity module in a mobile or cellular phone. It means that the phone number is connected to one SIM card and is used to identify phone number the user calls or sends an SMS message to.
MSISDN emphasizes in a unique way a subscription in a GSM or a UMTS mobile network.