There are several reasons why the LECs and CLECs don't support CID on DS1s with channelized inband signalling.
1. In the case of the SUPERTRUNK offering from Pacific Bell, CO switches have two sides so to speak. one is the 'trunk side' and the other is the 'line side'. The 'line side' provides the dialtone to subscribers, be they Loop-start or Ground-start. That being the case CID is a 'line side' feature. However, the 'trunk side' has very different uses, one being to connect with other switches for call completion. But trunks are also used for DID service, Operator access, Directory Assistance, etc. Because of the switch architecture the only type of service provisioned on DS1 is anything trunk oriented (in the switch).
When the software was written for SUPERTRUNK, CID was not considered. There was no format or hardware for it to work with. With more interest in PRIMARY ISDN, switch manufacturers saw no reason to spend money on developing this further, since PRI and BRI always had CID as a basic feature.
2. Now service providers can and do put Loop-start and Ground-start lines on DS1s with Channel Banks, but only the Loop-start lines have CID available as a feature and there are channel units both FXS and FXO types to support the feature. - I have never heard an explanation why CID is NOT available on Ground-start other than money, because the physical path is the same.
3. Of all the PBX systems I have work on over the years, none have supported CID on DS1s in relation to the items mentioned above where Loop/Ground-start is concerned. They only support CID for Loop-start on copper circuits!
I also echo JGideon's remarks about service providers concerning PRI, especially the tariffed ones! They won't budge for anything and then they think they are giving you the best deal in town! And then they wonder why they are losing revenue.
Hope this helps!
....JIM....
