We are using a Nitsuko 124i (I believe), and for some reason only two of the 5 extentions we are using will ring. Now I'm no phone tech (but I am the sys admin of the network) and some how this has fallen on me. I have a manual, but I cannot seem to figure out how to program the extentions to ring. I have used the check key to verify the ringer volume (pressing Check then vol up). Other than that, I am at a loss.

Now if I call from one extention to another, the extention that is being dial will ring, but if we get an incoming call then only 2 of the extentions will ring (we want all of them to). Thanks for your help!