IMSI [ International Mobile Subscriber Identity ]
IMSI = MCC+MNC+MSIN
MCC : Mobile Country Code [3 digits]
MNC : Mobile Network Code [2 or 3 digits]
MSIN: Mobile Subscriber Identification Number[ 9 0r 10 digits]
If MNC is 3 digits,then MSIN will be 9 digits.The total number of digits should be 15
This is burnt into your SIM[ Subscriber Identity Module ] card.When a mobile is switched on,it needs to be authenticated in order to access the network.
The IMSI is used for authentication.Once MS is authenticated and any further transaction will use TMSI[Temporary Mobile Subscriber Identity ] alloted by the network in order to prevent eavesdropping
NMSI stands for National Mobile Subscriber Identity formed by the combination of MNC+MSIN
MSISDN [ Mobile Station International Subscriber Directory Number ] or [ Mobile Subscriber Integrated Services Digital Network Number ]
MSISDN = CC + NDC + SN
CC = Country Code
NDC = National Destination Code
SN = Subscriber Number
Country Code (CC) : Up to 3 decimal places.
National Destination Code (NDC): Typically 2-3 decimal places.
Subscriber Number (SN): Maximum 10 decimal places
An MSISDN is limited to 15 digits.This is the number which you enter to make a call on your phone.
IMEI [ International Mobile Equipment Identity ]
IMEI =TAC+FAC+SNR+CD+SVN
The IMEI of your cellphone can be checked by keying in *#06#
It generally is of 16 bits,the first 14 indicates Equipment Identity and the last 2 indicates software version
When a Network queries for this IMEI,MS [Mobile Station ] sends this IMEI/IMEI-SV {SV :Software Version} and network can query EIR [Equipment Identity Register ] to get the status of
the equipment.EIR can reply back as,
0: Whitelisted In this case mobile is allowed service
1: Blacklisted In this case mobile is denied service.Blacklisted phones includes the stolen phones
2: Greylisted In this case mobile is allowed service but will be tracked. Grey listed phones might include those mistakenly left in restaurants, pubs
IMEI code 35-209900-176148-1 or IMEISV code 35-209900-176148-23 tells us the following:
TAC [Type Allocation Code]: 35-2099 - issued by the BABT (code 35) with the allocation number 2099
FAC [Final Assembly Code]: 00 - indicating the phone was made during the transition period when FACs were being removed.
SNR [Serial Number]: 176148 - uniquely identifying a unit of this model
CD: 1 so it is a GSM Phase 2 or higher
SVN: 23 - The "software version number" identifying the revision of the software installed on the phone. 99 is reserved.
Difference between IMSI,MSISDN and IMEI
There are three identities IMEI, IMSI and MSISDN. The IMEI is the mobile phone's identity which is burned into the phone.
The IMSI is the identity of the SIM card. And MSISDN is the phone number
MNP [Mobile Number Portability]
In case of MNP,you will have to change the SIM. The MSISDN will be mapped to a new SIM.Since IMSI is specific to SIM card,it changes in case of MNP
