How to resolve audio issues

The audio experience is critical to any callback interaction for agents and customers. If either party cannot hear audio prompts, hears choppy and inconsistent audio, or cannot hear the other party, the result can be a failure to connect customers and agents even if an interaction looks successful in the Call Detail report. This guide contains potential root causes and troubleshooting tips for audio-related issues that our engineers have seen in various telephony environments.

Overview

This general audio troubleshooting guide covers the following issues:

  • Voice prompts sound choppy or cut off for agents or customers
  • Agents and customers cannot hear each other

Issue: Voice Prompts Sound Choppy or Cut Off

In this scenario, agents or customers have reported that voice prompts played by Mindful Callback are difficult to understand. The audio may sound choppy as if it's cutting in and out, and the listeners may not be able to fully understand the prompts being played.

Potential Root Cause

This scenario can be caused by a Software-Defined Perimeter (SDP) with a comfort noise feature enabled. Comfort noise is designed to inject additional packets into an RTP stream to avoid any instances of complete silence. Our experience has shown that some comfort noise features can manage these extra packets incorrectly, resulting in moments of comfort noise overlapping or cutting off the audio prompts played by Mindful Callback.

Troubleshooting Tips

Use the following steps to determine whether comfort noise is the root cause:

  1. Determine whether the comfort noise feature is enabled on your SDP or other components in your telephony environment.
  2. If it is enabled, run a packet-capture (pcap) trace on an interaction that includes choppy audio.
  3. Filter the pcap trace to look for rtp.p_type==13 at the moment that the audio becomes choppy.
  4. If you find rtp.p_type==13 in moments of choppiness, disable the comfort noise feature and test to see if the audio prompts are clear.

Issue: Agents and Customers Cannot Hear Each Other

In this scenario, a connection is made between an agent and a customer, but they cannot hear each other speak. These calls can appear successful since the connection was established, but a conversation never actually occurred.

Potential Root Cause

We have seen this issue occur when firewalls alter the ports of SIP endpoints exchanged in a Software-Defined Perimeter (SDP). In this scenario, Mindful Callback and the SDP exchange SIP destinations within SIP messaging, and Callback assumes that the destinations (including ports) will not change. When a firewall alters a designated port, Callback continues to specify the original port for the RTP stream in a SIP Re-INVITE, causing a failure to connect.

Troubleshooting Tips

Use the following steps to determine whether ports are being changed unexpectedly:

  1. Perform a SIP trace on a call that experiences this issue.
  2. Analyze the SIP endpoints exchanged in the Record-Route parameter after a SIP INVITE to see if the port is being changed from the first instance.
  3. If the port changes, investigate your firewall rules to determine whether the firewall is responsible for changing the port.
  4. If the firewall is changing the port, update the configuration to ensure that the Record-Route parameter is not altered throughout the SIP session and test to see if both parties can now hear each other.