I have had some problems with 2 Callmaster phones. About three times a day two agents would receive a call and the customer can not hear the agent, the agent then needs to hit the mute button to turn it on and the mute button to turn it off and then both parties can hear each other. I have replaced their phones, moved them to different ports and also have taken notice that the calls do not come through the same trunk lines. Has anyone ever seen this problem and can possibly lead me in the right direction? I am stuck. 