Steve - All ICE phones (12) and 1 analog cordless ring and they are programmed to do so on all the lines, however when the problem happens none of the phones can answer the call. If you press the line button it says "Line busy" or somthing to that effect. I'm not sure if a real phone call is triggering the problem. I did make many, many calls into lines 5 and 6 to try to duplicate.
Today I removed the Group 880 that I created for the resident lines. Now I have it programmed for dial 9 access and then I excluded Lines 1 and 2 from the dial 9 group. Works good, guess we'll see what happens.
I haven't tried moving Lines 5 and 6 to Ports 3 and 4 yet. I could try that next.

Thanks