32022: ACK not received from your SIP endpoint

Twilio sent a 200 OK response for an inbound SIP call and did not receive an ACK from your SIP endpoint within 32 seconds. Twilio then terminated the call. SIP requires the calling endpoint to acknowledge a 200 OK to complete call setup.

• Your NAT configuration is preventing the ACK from reaching Twilio.
• Your firewall is blocking SIP signaling traffic.
• Your SIP endpoint is sending the ACK to the wrong IP address, or building the ACK with an incorrect Request-URI or Route headers.
• Your SIP infrastructure is rewriting Twilio IP addresses in the ACK or related SIP headers, which prevents Twilio from processing the request.
• Packet loss or another network disruption between your network and Twilio caused the ACK to be lost.

• Review your SIP endpoint configuration and confirm that it sends an ACK after Twilio returns 200 OK.
• Review your SIP endpoint logs to verify whether the ACK was generated, where it was sent, and whether any NAT or firewall handling changed the request.
• Build the ACK using the IP address in the Contact header of Twilio's 200 OK as the Request-URI. Send the request to the IP address in the Record-Route header from the same 200 OK.
• Do not replace Twilio IP addresses in the ACK URI or headers. Rewrite only your own addresses when your network requires NAT handling.
• Make sure your SIP device is configured to use the maximum supported retransmissions for SIP signaling.
• Review the call record in Console and download the SIP PCAP. If possible, capture a PCAP on your SIP endpoint and compare both traces to find where signaling diverges.

• Use SIP with Twilio Voice
• Inbound - Sending SIP to Twilio
• Troubleshooting your Trunk