MSISDN (pronounced as /’em es ai es di en/ or misden) is a number uniquely identifying a subscription in a GSM mobile network. Simply put, it is the telephone number to the SIM card in a mobile/cellular phone. This abbreviation has a several interpretations, the most common one being “Mobile Station International Subscriber Directory Number”.
A Subscriber Identity Module or Subscriber Identification Module (SIM) is an integrated circuit chip that is intended to securely store the international mobile subscriber identity (IMSI) number and its related key, which are used to identify and authenticate subscribers on mobile telephony devices (such as mobile phones and computers).
The cycle of mobile subscriber status are shown in below diagram: