Re: remove pstn-0
You are saying that your gateway is adding the word "pstn-0" before the number? If that is the case, then, there may be an option to make use of the name display field (where a callers name is sent along with a number , from the PSTN provider. Not used much outside of North America) to send information about which line the incoming call is using. In the Gateway settings there should be somewhere to edit or delete the default information.