Troubleshooting One-Way Audio Issues on Twilio Programmable Voice Calls

When a caller or callee can't hear the other party on a call, we refer to this as one-way audio. One-way audio can be caused by a number of factors including errors in the connection/handshake, problems on a specific call route, or issues at the source or destination. This guide is intended to help diagnose and resolve call audio quality issues related to one-way audio.

For more call audio guides, please see Troubleshooting Audio Quality Issues on Twilio Voice Calls.

Check for Twilio Incidents

Check the Twilio Status Page to see if there is an active incident, or an incident during the timeframe you reported issues, that could be causing your issues. For full details, please see Checking Twilio Service and API Status with the Status Page.

No incidents are listed that may be affecting calls: If you don't see an incident posted that may affect calls, then there is likely an issue elsewhere. Continue reading for additional troubleshooting.

An incident may be affecting calls: If you see an incident posted that may affect outgoing Twilio calls, please monitor the status, and then test again once the incident is resolved.

Identify the Issue

Attempt to ascertain the full details surrounding this issue:

  • Which side of the call is reporting the issue(s): caller, callee, or both?
  • Was the audio missing the entire time, or was audio lost at some point in the call?
  • Does this issue occur at the same time each call?
  • Are any parties using mute, placing the call on hold, or using an external headset or other accessory for calls?
  • Does this issue only occur with specific phone numbers or number types (landline, mobile, VoIP, etc.)?
  • Does this issue only occur when calling or receiving calls from a specific region or country?
  • Do other callers/callees report similar issues?

Once you are able to answer these questions, continue reading for additional troubleshooting.

Attempt to Replicate the Issue

Attempt another test call or two between the same phone numbers, and then try using the same Twilio phone number with different caller/callee phone numbers. The goal is to determine if this was a one-off, if the issue is limited to specific phone numbers or service providers, or if there may be a larger issue that requires investigation.

Issue is always replicated: If you are able to replicate the one-way audio issues on all calls in the same direction (to or from) with your Twilio phone number, we need to perform additional testing. Continue reading for additional troubleshooting.

Issue is sometimes replicated: If you are able to replicate the one-way audio issues only some of the time on calls in the same direction, check for any patterns:

  • If audio quality concerns are only coming from incoming callers using a specific service provider (or a small group of providers), then escalate to the caller's service provider.
  • If audio quality concerns are only coming from outgoing callees using a specific service provider (or a small group of providers), then continue reading for additional troubleshooting.
  • If no pattern can be found, collect additional examples, and then continue reading for additional troubleshooting.

Unable to replicate this issue: If you are unable to replicate the one-way audio issues, it's unlikely we will be able to address this report. Continue to monitor, and restart troubleshooting as needed if additional reports are received.

Escalate to Twilio Support

If you can rule out all of the above issues, Twilio's Support team can help investigate what went wrong. Please collect 3 or more examples of calls to or from the same Twilio phone number that have reported one-way audio issues from the last 24 hours, and include the following information:

  • Call SIDs
  • Description of audio quality issues
  • Variance of issues
  • Frequency of issues
  • Replication pattern

When you have collected this information, please share it with our Support team.

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