What is an MSISDN number?
MSISDN stands for Mobile Station Integrated Services Digital Network. This is the ‘phone number’ used to identify a device during calls or data sessions. When it comes to an IoT network, the MSISDN is crucial in making sure that the different components are connected securely.
What do the numbers in an MSISDN number mean?
When you call someone using a mobile handset, the recipient needs an identifier so they know it’s you who’s calling them. Without an identifier of some sort, the person has no way of telling who is trying to contact them. This also applies when a device is trying to connect to another device via an IoT network.
The MSISDN number is the part of the SIM that is used to identify the unique subscriber who is connected to a network. They are completely unique to a single SIM profile. SIM cards can only have one IMSI, but they can have multiple SIM profiles.
Not all MSISDN numbers are the same length; this is largely dependant on the number of procedures set by a network’s regulatory body and can change from country to country. They are usually 12 to 15 digits long, but 15 is the maximum. There are three elements that make up a MSISDN number:
- Country code (CC)
- Subscriber number (SN)
- National Destination Code (NDC)
All MSISDN numbers follow the same format:
CC+SN+NDC
For example:
44 (CC) + 2468 (NDC) + 123456 (NDC)
In this example, your device’s MSISDN number would be 442468123456.
MSISDN vs IMSI
Since they’re both unique identifiers, you may be wondering what the difference between an MSISDN number and an IMSI number is. To put it simply, an IMSI number is a technical identifier used by the network operator, whereas an MSISDN number is what most people would refer to as ‘the phone number’ for a device.
