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. CS Networks HLR lookup service cost is 0.009 EUR per lookup. With these costs CS Networks keeps the best price/quality on the internet.
IMSI or International Mobile Subscriber Identity is a unique number associated with all GSM networks and mobile phone users. This unique number is stored inside the mobile phone SIM card. The used network identifies each mobile phone subscriber by this particular number. The IMSI provides information such as location of call, user preferences and account status.
CS Networks HLR lookup service helps you send a "query" to both HLR and IMSI databases and receive the following information:
Is the number alive to determines if the number is in use - some people close their mobile contracts or stop paying their phone bills.
Is the phone number in use to determine if phone is switched on/off.
What is the current mobile network / mobile operator - to determines to which mobile provider a particular mobile number is subscribed. Often consumers change their mobile service providers, for example a Vodafone subscriber can move to D1 but keeps their Vodafone number.
Is the number in roaming - determines the roaming status of the mobile subscriber. ‘Roaming’ refers to the extending of connectivity service in a location different from where the mobile service is initially registered, usually when subscribers are in another country and their mobile phone automatically connects to a local service provider.
From where the phone number comes- determines to which country the number "belongs" to. This information is generally accessible and the HLR is not needed, because every number begins with a short code. For example code beginning with +447 is a UK phone number.
Download CS Networks HLR Specification.