Definition
MSISDN (Mobile Station International Subscriber Directory Number) is the subscriber number, the phone number people quote. On an IoT SIM it is what a user gives when reporting a fault, and what card information query uses to find the SIM from that number.
How it differs from ICCID
ICCID is the physical identity and stays put. MSISDN is assigned on the network and can change, for example when the number is replaced. Card information query accepts either.
Where the number is the key
- A fault report: The user usually knows the number, not the ICCID. Support looks the SIM up from the MSISDN.
- A batch file: Some imports and matches are a list of MSISDNs rather than ICCIDs.
- An operator API: Some operator interfaces require the MSISDN and will not take the ICCID in that field.
What a domestic number looks like
In China an MSISDN is usually 11 digits and starts with 13x, 14x, 15x, 16x, 17x, 18x, or 19x. On an IoT SIM the shape matches a handset number, but it is normally used for data, not for voice. The platform should check the format and that the number is not already on another live SIM.
The number inside card management
On the IoT Cloud Platform, MSISDN and ICCID are the two identities. Users and support quote the MSISDN. Batches and operator calls often use the ICCID. Card information query and SIM binding accept either. If the number changes, the platform copy has to change with the operator, or a lookup by the old number hits the wrong SIM. The number is also a join key for data billing and operator reconciliation.
Data only, and still an 11-digit number
The usual domestic MSISDN is 11 digits, beginning 13x, 14x, 15x, and the other ranges above. It looks like a handset number and is normally limited to data. Format and uniqueness are checked before it is saved. For an IoT SIM it is the identity the user side remembers, next to the ICCID printed on the card. It also appears in card lifecycle, in plan provisioning, and in operator reconciliation.
After a number change, can the old number still point at this SIM
MSISDN is the number the operator assigns to this IoT SIM and uses on the network side to identify the subscriber. In China it is commonly eleven digits. It is not the ICCID printed on the card body, which does not change after the factory. The same SIM keeps its identifier, while the number can change because of a replacement, a number transfer, or an operator adjustment. The platform should treat the number as a “current alias”: queries and API calls use the number in force now, and the old number goes into history with the time it stopped being valid. If the old number can still be matched exactly and used to suspend, the suspend lands on a SIM that has since been given that number. A user reporting a fault usually remembers only the number. Support should first see who that number is bound to now, and only then decide whether an operation is allowed. In SimtoLink operator integration, some APIs want the number and some want the identifier. Take the value the API requires before the call. Do not fill both identifiers into the same parameter.
When a SIM may have no usable number
When a number range has just been stocked and the operator has not finished opening the account, the identifier is already in stock and the number may still be empty. A query by number should say the number has not been assigned. It should not invent a placeholder that looks like a mobile number. A SIM with an empty number cannot do dialing or wake-by-message that depends on a number. It waits until the account-opening receipt writes the number back. If opening the account is repeated while the receipt is delayed, a second number may be issued. The platform should take the last successful receipt as current and mark the earlier unused number as void. A format check only looks at length and number-range prefix. Passing the check does not mean the number is open on the operator side. An international SIM’s number may carry a country code. Stock-in has to say whether the country code is stored, or the same number sometimes has 86 and sometimes does not, and reconciliation fails to match. Uniqueness is constrained among numbers that are currently valid. A historical number is allowed to appear again on an old record.
Which SIMs a bulk match on a number list will miss
A spreadsheet that suspends or queries in bulk by number misses stock SIMs that have not been assigned a number yet, and SIMs that have already changed number while the sheet still has the old one. A bulk job should output three result columns: matched, number does not exist, and number already replaced with the current identifier. Do not count the last two as success. When matching usage records, the number on the record is mapped to the number in force during that bill period, not to today’s number, or usage in the month of a number change is hung on the wrong SIM. If a user binds a SIM by entering only the number, also check the last four digits of the identifier or a message confirmation, which lowers the chance of binding the wrong SIM. A number shown to an individual user can be masked. A file exported for support needs permission. A full list must not be placed on a public portal page just because the number looks like a mobile number.
A country code or a leading zero turns one number into two rows
Stock-in, an API receipt, and a number typed by a user often spell the same number differently. One form carries the country code 86, one carries a plus sign, and one is treated as a number in a spreadsheet so a leading zero is dropped. Before matching, normalize to the project’s rule: domestic SIMs drop the country code and keep eleven digits; SIMs outside China keep the country code and must not be stored as a numeric type. Normalization is only for comparison. The store still keeps the original spelling from the operator receipt, and reconciliation uses that original value. A hand-typed number that is one digit long or short should be rejected outright. Do not auto-correct it into a neighboring SIM in a nearby range. If a message center or a voice allowlist has its own number field, it has to be updated together with the MSISDN that is currently valid. After a number change, updating only the query condition and not the message access number means the device keeps sending alerts to the old number. A bulk import uses a text column, not a numeric column, so scientific notation does not truncate a long number and open the wrong account.