Ryan, do you have a VOIB card in your system? If not, purchasing an IP phone is a waste of time.
Keep in mind that your system's 'XTS-IP' title only depicts what it is capable of being. Without the appropriate card installed and programmed, it won't support IP phones.
This is not a 'do it yourself' application. Trust me: Even trained professionals encounter difficulties in placing IP phones on an existing system.
Are you sure that you want to do this? We can't provide you with technician-level support here. We can only provide users guide assistance. I assure you that setting up an IP phone is not included there.
No offense, but it sounds like you should contact
www.vertical.com or 877-837-8422 to contact a certified dealer in your area to handle this matter. It isn't as easy as it seems.