I have a customer with an IP500 (6.0.0.0 (5219) with Edge 700-24 phones. They have one extension that initiates outgoing calls by itself periodically. The last time I was there I changed the jack, cable pair from jack to IDF, and cable pair from IDF feeder to MDF. I also changed ports from 3.10 to 3.4. This is the only phone that has the issue. When the phone is unplugged there are no issues. Any ideas of what else to check?