Overview

You encounter an issue where international incoming calls do not reach the TN (telephone number). Moreover, you do not see any call attempts hitting your SBC.

<supportagent>

Prerequisites

• Screenconnect access
• Hepic access

</supportagent>

Solution

To start with troubleshooting, we will need call samples. Open a ticket with Support, making sure to describe the issue and any symptoms you observe, and add at least two call samples in the following format:

• Calling From Number:
• Calling To Number:
• Date of call: dd/mm/yy
• Time of call: xx:xx am/pm (time zone)
• Result: ex: dropped call, garbled audio, etc.
• Trouble observed: Inbound / Outbound / Both directions

<supportagent>

Once you have the details and call samples from the customer, proceed with the steps below:

1. From one of the Screenconnect VMs in the corresponding Data Center look up the customer samples in Hepic.
   
2. Proceed based on your findings. Make sure to pay attention not only to errors but to numbers format and any anomalies (see Known Cases).

Known Cases

Incorrect prefix added by AT&T

In one case, the SIP traces indicated that AT&T was adding a +1 at the beginning of the international number:

In red, we can see the extra "+1" is placed incorrectly for this UK number (ie +144 instead of +44).

As the IP 12.194.41.30 highlighted in green belongs to AT&T, the correct process was to escalate this issue to AT&T so they can find the root cause.

AT&T found out that the root cause in such a case was that the telephone numbers called were not fully provisioned on their side in the GNF (global numbering formatting) table. They adjusted the configuration and the issue was resolved.

</supportagent>

Based on the troubleshooting the Support team will either take action to fix the issue on our side or reach back with findings and any next steps required from you.

Verification

Once the root cause is fixed, try to replicate the issue to confirm that it is no longer there.