First Contact Extension Number

I've installed the Ring Alarm System in my office. When I did initial setup the first contact accepted an extension number i.e. 999-999-9999 x999 however when I just did a test, the call went all the way to the last (third) contact. I checked the number for first contact and now see that it will not accept an extension number! This Can't be true; these are being marketed to businesses, don't most small businesses, these days, have a phone system with an auto attendant??? How do I get the system to call the office that's alarming and dial an extension to ring phones within the office? otherwise there will be no way to verify or cancel an alarm with our verbal password. Is there a workaround or patch? thanks for your assistance, Steve Miller