Log into your box.
Type cmd gkroute xxxxxxxxxxxxx
where the “x” ‘s are the phone number that the carrier is sending you. Normally it will country code, area code and number.
If the gateway does not answer with a message like this:
Public Endpoint matches
1281* xxx.yyy.www.yyy:1720
No Public Proxy candidates
No Private Endpoint candidates
The gateway need to reply with its own I.P. address ,or it is not ready to accept that number.
You do not need to type the whole phone number, the first few digits should be enough, like country and area code.
No gateway will route calls until this step pass.
Good luck!!!!