A radio access network element (101) obtains a permanent subscriber identity (IMSI) of a User Equipment (103) in an LTE wireless communication system (100) by sending a “fake” service reject message to a User Equipment which has attempted to attach to a cell (102) in a request for services message which includes its S-TMSI. The reject message may include a cause code which results in the UE attempting to attach again, this time using its IMSI. The fake service reject message may be generated in a an eNode B serving one or more macrocells or a evolved Home Node B serving a small cell.