Switchvox - Why are Outgoing calls showing the wrong number on my Digium phones?

Outgoing calls showing the wrong number on my Digium phone, or the Caller ID changes on the phone.

This usually occurs when the Switchvox is connected to a Gateway.
Log into the Gateway appliance.
Go to Configuration > SIP Endpoints and modify the SIP Endpoint. 
Set the Enable Advanced Options to YES and click on the Call Settings tab. 
Set the Send Remote-Party-ID to NO 
Save Endpoint

Place a test call and see if the issue is resolved. If it is still occurring, verify that you modified the correct SIP Endpoint. If so, call Technical Support for further assistance.