I have two separate instances of VVX 400 series phones acting strangely. The phones will act as if someone is pressing keys , mostly the hook switch up and down, all by themselves. In one instance, the phone is part of a ring group, and when a call is inbound to the group, it will occasionally answer the ringing call all by itself. While the phone is idle, you can see the phone going off hook, and then hanging up all by itself. The other phone will do similar things like take the current Speakerphone call, and switch to handset without being touched. These phones are attached to 2 different 7100's on 2 separate unrelated sites. We have replaced the phone with another new vvx400, we have replaced cabling for both these phones, I have tried different switch ports on the 7100's, and have checked for other sources of interference with no luck. I am not sure how to further troubleshoot the issue. I am thinking of trying Shielded cable if outside interference is the issue. On one of the phones, I have moved the device to a different location in the building and didn't see the issue follow. This leads me to believe there is electrical noise near the device or cable where it is currently installed. Any advice to help me resolve these issues would be greatly appreciated.
