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Elastic SIP Trunking Codecs

Supported Codecs

Twilio supports PCMU and PCMA for Elastic SIP Trunking.


When Twilio receives outgoing traffic from your communications infrastructure to the PSTN, we will match the first supported codec in the SDP offer. Twilio supports PCMU and PCMA.


When Twilio directs incoming traffic from the PSTN to your communications infrastructure, it will send PCMU and PCMA in the following order in the SDP parameter.

  1. PCMU
  2. PCMA
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