Since number portability started being widely deployed few years ago, it has become increasingly difficult to reliably identify in what network a mobile phone number belongs to just by analyzing the number.
HLR or Home Location Register is a central database containing details of each mobile phone subscriber that is authorized to use the GSM core network. The HLR lookup (referred also as Mobile Network Query or IMSI lookup or MSISDN lookup or Mobile Number Portability lookup service) is a method of querying the mobile network's HLR allowing you to check in real time, whether a mobile number is active or not and which network it currently belongs to.
Each SIM card has a unique number called IMSI (International Mobile Subscriber Identity) which is used by the network to identify the SIM. The MSISDN (Mobile Subscriber Integrated Services Digital Network-Number) is the actual mobile number of the SIM card and is used by the network for routing calls to the subscriber. The IMSI together with the MSISDN are the two most important numbers used to identify the mobile phone subscriber.
When you submit a MSISDN to our HLR lookup service, our system checks whether the mobile number is valid or not. If so, it returns the operator name, the country, if it is ported or not, the IMSI and the MCC/MNC (Mobile Country Code/Mobile Network Code) associated with it.