CTX-100 w/RCOU/RCOS line cards and (3) BWDKU station cards.
One Ext.(#238) randomly calls the receptionist or operator (#200) on the intercom. This occurs about once a day or less. I have tried deleting the ext. and rebuilding it also moving to a different ext. (#248), the problem followed the change. Will a intermittent short in the ext pair cause this? I could meger this pair of wires or change to a different pair. I have looked for a short in punch down blocks and phone jack. Extension (#200) is a DK3020SD w/ (2) DADM3220's. The VM is a IES32 w/ 250 center port and 251 and 252 as VM ports. Thanks for any input, Lyle Roy

What kind of phone is Ext 238? Is it analog, VM port, digital phone?

If it is an analog phone there is probably a short in the cabling somewhere.

Does ext.238 have a DSS button of ext.200? Could be a sticky DSS key. Or try swapping the phone for ext.238 with another and see if the problem follows the phone.