Saturday, 26 January 2008

ISDN (wierd) problem

Well today I discovered an odd issue with a new customer network. For some reason, if the External phone number mask on a phone was anything else than what was deemed "valid" such as when (example numbers used):

Trunk number: 01234 115115
DDI number: 01234 115200
Valid EPNM to send is "200"
Invalid number such as 01234 115200 results in CLI presented to called party as 01234 115115.

...then the call would not complete. IE, if I sent 01234 115200 to the PSTN then the following symptoms would occur:
  • IP Phone gets busy tone
  • My mobile phone would ring out for half a ring, presenting 01234 115115 before hanging up. Odd!
  • What's more is the debug isdn q931 from the Cisco router:

*Jan 26 09:01:29.606: ISDN Se0/0/0:15 Q931: Applying typeplan for sw-type 0x12 is 0x0 0x0, Calling num 01234115200*Jan 26 09:01:29.610: ISDN Se0/0/0:15 Q931: Applying typeplan for sw-type 0x12 is 0x0 0x0, Called num 07989163892*Jan 26 09:01:29.610: ISDN Se0/0/0:15 Q931: TX -> SETUP pd = 8 callref = 0x0117 Bearer Capability i = 0x8090A3 Standard = CCITT Transfer Capability = Speech Transfer Mode = Circuit Transfer Rate = 64 kbit/s Channel ID i = 0xA98399 Exclusive, Channel 25 Progress Ind i = 0x8183 - Origination address is non-ISDN Calling Party Number i = 0x0081, '01234115200' Plan:Unknown, Type:Unknown Called Party Number i = 0x80, '07989163892' Plan:Unknown, Type:Unknown*Jan 26 09:01:29.822: ISDN Se0/0/0:15 Q931: RX <- CALL_PROC pd = 8 callref = 0x8117 Channel ID i = 0xA98399 Exclusive, Channel 25 Notification Ind i = 0xE8*Jan 26 09:01:33.614: ISDN Se0/0/0:15 Q931: RX <- ALERTING pd = 8 callref = 0x8117*Jan 26 09:01:33.654: ISDN Se0/0/0:15 Q931: TX -> DISCONNECT pd = 8 callref = 0x0117 Cause i = 0x80AC - Requested circuit/channel not available*Jan 26 09:01:33.830: ISDN Se0/0/0:15 Q931: RX <- RELEASE pd = 8 callref = 0x8117*Jan 26 09:01:33.834: ISDN Se0/0/0:15 Q931: TX -> RELEASE_COMP pd = 8 callref = 0x0117

Yes that's right! The call completes, yet the Q.931 debug says the bearer isn't available! It did make me wonder whether i'd configured too many bearers than the customer had paid for, but by a stroke of luck I determined that sending the correct CLI to the PSTN allowed the call to proceed:

*Jan 26 09:04:53.326: ISDN Se0/0/0:15 Q931: Applying typeplan for sw-type 0x12 is 0x0 0x0, Calling num 200*Jan 26 09:04:53.330: ISDN Se0/0/0:15 Q931: Applying typeplan for sw-type 0x12 is 0x0 0x0, Called num 07989163892*Jan 26 09:04:53.330: ISDN Se0/0/0:15 Q931: TX -> SETUP pd = 8 callref = 0x011A Bearer Capability i = 0x8090A3 Standard = CCITT Transfer Capability = Speech Transfer Mode = Circuit Transfer Rate = 64 kbit/s Channel ID i = 0xA98399 Exclusive, Channel 25 Progress Ind i = 0x8183 - Origination address is non-ISDN Calling Party Number i = 0x0081, '200' Plan:Unknown, Type:Unknown Called Party Number i = 0x80, '07989163892' Plan:Unknown, Type:Unknown*Jan 26 09:04:53.534: ISDN Se0/0/0:15 Q931: RX <- CALL_PROC pd = 8 callref = 0x811A Channel ID i = 0xA98399 Exclusive, Channel 25 Notification Ind i = 0xE8*Jan 26 09:04:56.770: ISDN Se0/0/0:15 Q931: RX <- ALERTING pd = 8 callref = 0x811A*Jan 26 09:04:58.538: ISDN Se0/0/0:15 Q931: TX -> DISCONNECT pd = 8 callref = 0x011A Cause i = 0x8090 - Normal call clearing*Jan 26 09:04:58.706: ISDN Se0/0/0:15 Q931: RX <- RELEASE pd = 8 callref = 0x811A*Jan 26 09:04:58.710: ISDN Se0/0/0:15 Q931: TX -> RELEASE_COMP pd = 8 callref = 0x011A

4 comments:

Mike Aossey said...

Jed you are the Man! I have been trouble shooting this same issue for about 3 hours and I would have never changed the CID if I would not have read your blog post. Thank you!

Anonymous said...

It's posts like this that are exactly the reason why I started this blog. Thanks Mike!

Jed.

Danny said...

Same here. I had the same problem. I migrated from Cisco Callmanager 4.1.3 to 6.1.3 with the same configuration. After changing the DID number the call wasn't cut short anymore from the inside. I'm not quite sure who disconnected, the gateway or the Callmanager because that was the only thing which got changed.
Maybe it was all a coincedence and the Telecom changed something. (Unlikely)

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