Transit Network Selection behavior on PGW2200

[damirs]

I have a Cisco PGW220 with two SLT?s and AS5850 as media gateway. Everything is working for now but I have a problem when Carrier Selection is about to be implemented. Telco is using TNS specification from ITU-T Q.763 on their side and Carrier ID is 1023. PGW is configured so that calls with this Carrier ID are forwarded via SIP to component that will do user authentication (ROUTE result with TNS config referencing Carrier ID to this result set).

When IAM message is received by PGW from Siemens EWSD PBX snooper shows following

TRANSIT NETWORK SELECTION 0x23

LENGTH: 0x03 OPT. DATA 0x21 0x01 0x32

TYPE OF NETWORK IDENTIFICATION 2 National_Network_identification

NETWORK IDENTIFICATION PLAN 1 three_digit_carrier_identification_code

CARRIER ID CODE 102

CIRCUIT_CODE 3 Unknown_or_spare

PGW responds with No Route To Destination reason code in REL message.

When IAM message is received from Ericsson AXE PBX snooper shows following

TRANSIT NETWORK SELECTION 0x23

LENGTH: 0x03 OPT. DATA 0x21 0x01 0x32

TYPE OF NETWORK IDENTIFICATION 2 National_Network_identification

NETWORK IDENTIFICATION PLAN 0 unknown

PGW routes the call based on other parameters (in this case on B Number Analysis) but does not strip TNS fields.

Any help on this since subject is not covered in almost any document I could find on cisco.com

[mchin345]

I don't see any way to workaround it on the PGW side. The only way could approach is with your ISP such that the PGW could modify the code

[damirs]

I am dealing with the government owned telecom and only answer that I can get from them is ?problem is on your side?.

Thanks for the answer

[anikas]

It sounds like it depends on your dialplan.

I was able to find the following URL:

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_white_paper09186a00801d8d94.shtml

You can capture and MDL trace and look to see what is happening for the specific IAM. The other option you can try is to use the SIMWriter tool to see what the dialplan would do given the Calling and called party number.

Both of these will tell you if the DIAL Plan may be affecting the outcome.