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Incoming Calls from External Caller are Getting Busy Signal then Call Fails

Andriy Rybalchenko
  • Updated

Overview

The incoming calls from the external caller are getting a busy signal "Decline (603)", and then the call fails.

<supportagent>

Prerequisites

  • APIM admin role
  • Screenconnect access
  • PSX 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. As this is a STaaS case, we need to verify the configuration directly on PSX first. Find the called number(s) under the Subscriber and Standard Route views to confirm whether the configuration is correct (you can cross-check with other numbers for the customer).
  2. If the configuration is correct, from one of the Screenconnect VMs in the corresponding Data Center look up the customer samples in Hepic.
  3. 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

The issue on the caller side

In one case, we were receiving an extra 1 on the From header, as observed in SIP traces:

Ie the incoming calls contained a “1” on the From header of the SIP call, and on the SBCs the calls are normalized to E.164 format, so the call was coming as +118778782468 instead of +18778782468.

In such a case, relay the findings to the requester and ask them to reach the Caller to fix the issue on their side.

</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.

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