I have a problem with one of my customers that I have never seen or heard of. When they try to conference using their 4620 IP phones, it drops both callers that they are trying to conference. I have seen problems with Phone Manager but never with a hard phone like this. I couldn't believe it so I called my contact and went over the steps again to make sure that they were doing it correctly and they were. So I had him try with me on the line and, sure enough, I got dropped. They are running 2.1.51. Anybody else seen this?