Specifications of signalling system No. 7 : recommendations Q.930 - Q.940 / International Telecommunication Union
Public land mobile network : interworking with ISDN PSTN: recommendations Q.1000 - Q.1032 / International Telecommunication Union
Interworking with satellite mobile systems : recommendations Q.1100 - Q.1152 / International Telecommunication Union
Specifications of signalling systems Nos. 4 and 5 : recommendations Q.120 - Q.180 / International Telecommunication Union