Speaker Volume fades out after extended period

[upstateny]

On a legend r7 the volume fades out on a speakerphone after approximately 10 minutes. it is after an extended time and is definitely not clipping of the conversation - the existing vendor put a MFM and Polycom on the phone and problem still happens - it happens on several phones and has happened consistently for quite some period of time - the lines in are going to mlx cards from a channel bank - any thoughts??? - thanks!

 

[Pepperz]

Try feeding the same phones from a different MLX card, if problem still persists, look at the channel bank. (Can rule out channel bank if problem happens on inside calls as well.)