I have a dect cordless phone and would like a second phone in another room. Do I need a telephone connection in that room to use the 2nd phone? The DECT phone I now have is from Eircom and is now 2/3/4 years old. Does the 2nd phone have to be the same make as the first one to be of any use? The Eircom dect phones were BT I think, so do I need a BT phone to be compatible with what I now have.