Enable Voice Trace for Troubleshooting Twilio Call Audio and DTMF Issues

Voice Trace is an important tool Twilio's internal teams use to identify issues with call audio and touch-tone keypresses (DTMF). We have recently added a Voice Trace option in Console, so now users can quickly recreate issues with full packet captures in place, hastening the troubleshooting process. This guide will explain how Voice Trace works, and how to enable or disable it.

Notice: Voice trace captures are stored by Twilio for 14 days. Depending on your use case, your reasons for enabling voice trace, and the laws of the jurisdiction(s) you operate in, you may need to obtain consent from the parties to the call before requesting Twilio to enable voice trace. Please be sure you have all necessary consents from relevant parties before enabling voice trace. 

What does Voice Trace do?

While Voice Trace is enabled on a project or subaccount, Twilio's media servers silently create logs to capture each SIP and RTP media packet transmitted for your calls. This logging produces no perceptible quality or performance impact to users - calls will continue flowing as normal. Once the call has been completed, our Support team can pull these logs to investigate all manner of call audio quality or DTMF issues:

  • What network conditions may have caused or exacerbated the issues?
  • Which side of the call or conference participant caused the issues?
  • How were DTMF keypress signals transmitted?
  • Why did the call(s) not go as planned?

Restrictions: Please note that Voice Trace packet capture logs contain confidential and proprietary system details, and therefore can't be shared outside of Twilio. This logging is also not compatible with <Pay> and the corresponding PCI Mode option, as we don't capture this packet data in PCI mode.

Enable Voice Trace

Voice Trace can be enabled from the Twilio Console:

  1. Login to your Twilio project at www.twilio.com, and then access the desired subaccount (as needed).
  2. Access the Voice Settings page in Console.
  3. Scroll down to the Voice Trace option, and then click the switch to Enabled.
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  4. Click Save
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Troubleshooting with Voice Trace active

Once Voice Trace is active, Twilio will begin capturing SIP and RTP media packets in the background of all supported calls. At this point, we ask that you attempt to replicate the reported issues, so that we can capture the packets and investigate.

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 DTMF or audio quality issues on all calls in the same direction (to or from) with your Twilio phone number, we ask that you Escalate these calls to Twilio Support.

Issue is sometimes replicated: If you are able to replicate the DTMF or audio quality 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), we ask that you Escalate these calls to Twilio Support.
  • If no pattern can be found, collect additional examples, we ask that you Escalate these calls to Twilio Support.

Unable to replicate this issue: If you are unable to replicate the jitter-induced audio quality 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

Twilio's Support team is happy to help investigate your call quality issues. We ask that you collect 3 or more examples of your test calls (after enabling Voice Trace) to or from the same Twilio phone number that have reported repeated DTMF or call audio quality issues from the last 24 hours. Please include the following information:

  • Call SIDs
  • Description of DTMF or 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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