Attempting to program a loudspeaker page button on a phone. The instructions in the manual do not work. I've done this before where you hit the button and assign Intercom 70 to it. I thought there was a different area than Central Tel Program to do it in. When we access central tel program and hit the programmable button it only allows us to change the ring type on the current line programmed on it, from delayed to immediate. Won't let us change the feature on it. Any ideas?