Why Does a VoIP Call Transfer Work Internally but Fail to External Numbers?

A transfer may work between internal extensions but fail when the destination is an external number because of dial plan, permissions, or carrier routing rules.

What to check

Compare transfer type, number formatting, outbound permissions, caller ID, provider response, and device behavior. Record timestamps and test with approved external destinations.

Recommended next step

Correct the external transfer route and retest with the service provider if needed. Informatix Systems can troubleshoot VoIP call routing.