If i'm gonna use IP telecom by upc i only have to plug in a ip phone on a rj45 into my modem. i dont have to provide a username / password. will i be able to use it in mce?
Your phones will have to be plugged into the internal network of LMCE. Since the UPC modem is on the outside, LMCE has no idea what is going on there. So even though it may work as a stand-alone solution for voice over IP, you cannot use it this way in LMCE.
UPC does not give you a username and password for a SIP account, so you'll have to find this elsewhere. You could try something (almost) free at first. Skype will NOT work.
Hope that helps,