HLR lookup
Definition
A network query that checks whether a mobile number is active and which mobile network currently serves it.
HLR lookup, explained
An HLR lookup queries the Home Location Register, the database a mobile network keeps about its subscribers. Through a lookup provider, a business can learn whether a mobile number is currently active, which network it belongs to (even if it was ported), and sometimes whether it is roaming. It only applies to mobile numbers on cellular networks; landlines and many VoIP numbers do not have an HLR record in the same way. Platforms and messaging providers use HLR data to clean contact lists, route messages correctly and screen sign-ups, for example by refusing numbers that appear inactive or do not belong to a mobile network. It is related to, but not the same as, a line type lookup, which classifies a number as mobile, landline, VoIP or toll-free from numbering data. Results depend on the provider and the network and are not always perfectly up to date. A number failing an HLR or line type check is one common reason an app says a phone number is invalid.
Related terms
Line type lookup
A check that tells an app whether a number is mobile, landline or VoIP, and often which carrier owns it.
Carrier
A mobile network operator or provider that issues phone numbers and delivers calls and texts.
Number porting
Moving your existing phone number from one carrier or provider to another so you keep the same number.