ETR 106 : european digital cellular telecommunications system (phase 2): example protocol stacks for interconnecting service centre(s) (SC) and mobile-services switching centre(s) (MSC) (GSM 03.47) / European Telecommunications Standards Institute
ETR 103 : european digital cellular telecommunications system (phase 2): radio network planning aspects (GSM 03.30) / European Telecommunication Standards Institute
Numbering, addressing and identification : recommendation GSM 03.03: version 3.5.0 / European Telecommunications Standards Institute