Switchvox - Why Does The Number Dialed Change on the Phone Display During A Call?
You most likely have a Gateway appliance in between your PBX and provider.
To resolve this issue please log into Gateway appliance.
Go to Configuration > SIP Endpoints and modify the SIP endpoint.
Turn on 'Enable Advanced Options' and go to Call Settings Tab.
Set 'Send Remote-Party-ID' to NO and then test.
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