A call source refers to the subscriber or incoming trunk that originates a call. A call source name is specified for each call source. Generally, there are three types of call sources: A interface, Iu interface, and incoming trunk.
Based on the call originator, the MSC queries the corresponding table to obtain the call source name. The detailed number analysis procedure is as follows:
If a call comes from the A interface (that is, from a 2G mobile subscriber who is visiting the local MSC), the local MSC queries the data about location area and cell to obtain the call source name based on the GCI.
If a call comes from the Iu interface (that is, from a 3G mobile subscriber who is visiting the local MSC), the local MSC queries the data about location area and service area to obtain the call source name based on the SAI.
If a call comes from the trunk side (that is, from a fixed subscriber or a subscriber of other MSCs), the local MSC queries the office direction data to obtain the call source name for BICC trunks or queries the trunk group data to obtain the call source name for the other types of trunks, for example, ISUP, TUP, PRA, and SIP.
A call source specifies the source of a call. The MSC processes calls differently depending on specific call sources. You can run ADD CALLSRC to configure a call source.
When used as an input parameter, the call source name is referenced by many tables, including the Called Number Pre-analysis table (ADD CLDPREANA), Call Authority Check table (ADD CALLPRICHK), Auxiliary Signaling table (ADD AUSSIG), Service Check table (ADD SRVCHK), Caller Feature Analysis table (ADD CLICRTANA), Caller Number Analysis table (ADD CNACLR), Call Prefix Processing table (ADD PFXPRO), N-CSI Configuration table (ADD NCSICFG), Auxiliary Number Processing table (ADD AIDNUMPRO), CLIP Processing table (ADD CLIPRO), and Outgoing Number Pre-processing table (ADD OUTNUMPREPRO).
Based on a call source name, the MSC can obtain other configurations related to the call source, such as DN set, route selection source name, and failure source name. In addition, based on a call source name, the MSC can check certain features of the call source, such as delay digit collection duration.
