I have a Partner system that is acting strangely. x10 is an 18D phone. The other 4 phones are Partner 6s. The problem I am having is on x13. It has one of the 6s. When we try to pick up line 1 or line 2, we get nothing. If we pick up line 3, there is dialtone. I have checked line assignement multiple times. I have also checked another known good phone. Any ideas?

JR