HLR checking, sometimes called HLR query or HLR Lookup, provides a direct network level check against any GSM mobile number. The check can provide detailed information such as the original network a mobile number was assigned, if the number has been ported to a different network, which ported network it has moved to, if the mobile has been turned on recently and what country the mobile was last used. All checks are non-invasive and remotely performed - this means the user of the mobile does not see anything on their phone.