I am looking for some help installing an analog phone on our M8x24-DS. I believe the software is 5.1. I have successfully set up 4 regular extensions, which is all we need. My manager would like a portable phone, so I figure the easiest solution would be an ATA2, which I have. However, I haven't the slightest idea on how to install it. Does it work like a regular extension? Can the phone still access any features of the system?