The Number Continuity Service: Part II - GSM <-> CDMA Seamless Technology Change

Even with the predominance of the GSM technology, there are instances when the only coverage for a GSM outbound subscriber is from a CDMA (IS-41) network (that includes many fixed networks in the USA and the CDMA based Globalstar satphone services). Symmetrically a CDMA subscriber roaming in a GSM network after changing for a GSM handset, will need the number continuity service to receive his calls and SMS. Roaming Hubs able to convert the two signalling systems are required. We explain the differences into the mobility protocols (MAP GSM and MAP IS-41), the TCAP protocol (ANSI and ITU) and the network layers (14 bits ITU and 24 bits ANSI Point Codes). The eight possible combinations are handled by a multi-standard Roaming Hub architecture. Detailed protocol traces are included.