Incoming Call Forward to PSTN for the calls originating from PSTN

[Halsser]

I have an issue with calls originating from PSTN and redirecting back to PSTN. That mean when I have incoming call from PSTN, and I have the call forward to PSTN mobile number on my extension the call does not go through but get disconnected.

• Calls from internal extension get forwarded to PSTN.
• outgoing /incoming calls working properly without forward to PSTN.
• calls originating from PSTN and forwarded to internal extension works.
• The call follows: PSTN caller ->E1/PRI ->Voice Gateway ->SIP Trunk -> CUCM->SIP->IP phone
• I used outgoing translation profile to configure my router to send any number within my subscribed DID range as CALLING NUMBER (CLID)  

I keep getting:

SIP/2.0 480 Temporarily Not Available and cause value=20

I am looking for your assistance with this issue.

[jaheshkhan]

same issue for me.

[Nithin Eluvathingal]

External calls forwarded from internal to external numbers will fail because the ITSP will reject the call. By default, the calling number will be the external call's number, and the ITSP will reject this because you are not supposed to send calls with a calling number outside your DID block.

However, some ITSPs translate this to the pilot number of your DID block and process the calls.

ITSP does this for billing purpose.

In your case, I believe the ITSP is rejecting the call.

The trace will provide more information on what really happened. A setting on the CUCM trunk or gateway configuration page can fix this problem. In the outbound call section, by default, it would be the "Originator." Change this to the Last or First Redirecting Number. This could most likely solve your issue. This solution is based on an assumption. An exact fix can be provided if you share the logs from the gateways, which will shed light on what really happened for the calls to fail.

Debugs from the gateway could help us understand what really happened. We need the debug CCAPI inout, If the gateway is SIP, collect "debug CCSIP messages", and if the connections is PRI collect "debug ISDN Q931".

If the Forwarded calls cannot be seen on the call gateway, we need to look into the CUCM traces

[Liam1809]

@HalsserPlease run a 'debug ccsip messages' and 'debug isdn q931' and post the full results.

[tamseel8345]

how the SIP trunk or voice gateway handles call forwarding to PSTN. The "480 Temporarily Not Available" error usually indicates a routing or signaling issue. Try verifying your call forwarding settings on CUCM and ensure that the SIP trunk has the correct configuration for call forwarding to PSTN. Double-check your outgoing translation profiles and ensure that the correct calling number (CLID) is passed through without any conflicts. Additionally, check if the PSTN mobile number has the proper routing in your gateway settings.

[Vaijanath Sonvane]

When external calls are forwarded back to PSTN numbers, then some ITSPs look for Diversion Header with authorized DID number. You can apply SIP Profiles with Diversion Header in it. Check the debugs on your router to see what you are sending to ITSP and update the SIP Profile accordingly. 

[tamseel8345]

Based on the '480 Temporarily Not Available' error, it seems there’s a routing issue with the call forwarding back to PSTN. I recommend checking your Voice Gateway translation profile and dial-peer settings to ensure proper routing for PSTN-to-PSTN calls. Also, verify that the SIP trunk and CUCM configurations are correctly handling the forwarded calls. Reviewing the logs might provide more insights.