Why we need msisdn when we have imsi?

Question

M2M devices and data cards without voice services may not need an MSISDN, how are such records maintained on the HLR? Is it mandatory to have an MSISDN associated with every IMSI record on the HLR? If yes, can we just have a dummy/fake MSISDN associated in such a case so to avoid consuming/wasting a real MSISDN?

Answer 1

MSISDN stands for "Mobile station international subscriber directory number". This number is used to make a call to an user. One SIM card can have one IMSI number but it can hold multiple MSISDN numbers. MSISDNs can be changed but IMSI can not be changed.
One more thing, IMSI information is kept in UE and network. It should not be shared with others.

Comments

msisdn is nothing but the ph no right??? if so how can 1 sim have multiple msisdn ???

Answer 2

Yes one SIM can have multiple MSISDN particularly for roaming purposes wherein the user can have a local number + Home PLMN number. These are customized SIM's and are used for receiving calls on local numbers with local call rates