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FAX Support - Troubleshooting T.38 Over SIP Faxing Problems

FAX Support - Troubleshooting T.38 Over SIP Faxing Problems

Problems Faxing over SIP Provider with T.38 Protocol:

  1. Check the Error Logs for fax errors (go to Server > Error Logs).

  2. Customer must verify that their SIP Provider supports T.38 over SIP protocol for faxing (this is necessary to use SIP faxing).

  3. Verify that the ports UDP 4000-4999 are open to the Switchvox server on firewall/router.

  4. Run a Packet Capture to determine if the traffic is reaching the Switchvox server (Go to Server > Advanced Debugging > Start Debugging Session > Packet Capture).

  5. Fax Settings for VOIP Providers can be found under Setup > VOIP Providers (modify Provider) > Fax Settings. The default settings should work in most cases.

Note: We can only verify that the Switchvox server is configured properly. Some VoIP Providers and equipment vendors may be compatible with Switchvox's T.38 implementation. Interoperability testing should be performed to make sure that SIP T.38 faxing using your provider or vendor will work with Switchvox.