Error communicating with your SIP communications infrastructure

There was a problem communicating with a specific endpoint of your SIP communications infrastructure. This means there was either a lack of timely response, an error response or an invalid response from your SIP endpoint. This may result in increased call setup times or even failed call depending on the failover configuration for your Elastic SIP Trunk or SIP application. Twilio will make multiple attempts to deliver calls to your endpoint and each failed attempt will have its own notification. The notification will have details about the specific error response and the SIP URI that causes the failure.

• Your SIP endpoint is not reachable due to network connectivity issue between Twilio and your system
• Your SIP endpoint is not responding (service down or maintenance)
• There is a firewall in your network that is blocking SIP traffic from Twilio
• Your SIP endpoint is sending an error response, such as SIP 500 response.
• The SIP URI specified in your Trunking Origination URI, TwiML or REST API call is invalid
• Your SIP endpoint does not support TLSv1.2

• Ensure the SIP URI used in the request is correctly configured.
• For details on how to configure your Origination URIs for SIP trunking, please see Origination settings.
• For SIP interfaces verify that your SIP URI in your TwiML or REST API call, see Receiving SIP from Twilio.
• Ensure you've allowed Twilio's IP address ranges and ports on your firewall for SIP signalling and RTP media traffic, see IP addresses - Trunking or IP addresses - SIP Interface
• Ensure that your SIP servers are running properly and is properly processing calls from Twilio.
• Ensure that your SIP servers support TLSv1.2, or configure your account to allow TLSv1.0+