I have a CME installed in my office. I have a couple of users who will be working out of another office across town. We have a VPN LAN-to-LAN link between the 2 locations. Can I use 7960 phones for the users at the temp location and get service from my CME?
That certainly is possible. You'll need to consider QoS. Is this a DSL/Cable link that you have no control of? You'll also need to consider 911. If a remote user dials 911 and the call goes out a gateway at your main office, then trucks will roll to the main office.