Here is the issue. I have my home and my company on my elastix. I want to be able to pick up any of the phones in my house and dial out thru the house sip trunk. Then I want to be able to pick up any of my office phones and dial out thru the office trunks. I know I can assign 9 then number and 8 then number to get different outbound routes. But here is the question. HOW DO I PREVENT A PHONE FROM EVER ACCESSING A PARTICULAR TRUNK WHILE HAVENING ACCESS TO THE OTHERS? Kids have figured out if the house trunk is busy to dial 8 then number and they can dial out on my office lines. In a Typical PBX this is called class of service. Any ideas.