audio levels during Skype meeting

Good morning!  Are there any SfB Server administrative controls available to modify level or adjust AGC for inbound audio from phones or interop devices like Polycom RealConnect on premise?  We occasionally get complaints from users that inbound audio from Polycom Group Series or call phone calls is low during Skype meetings.  Skype > Skype audio and Polycom > Polycom audio is good, low volume seems to only affect interop calls and some cell phone calls.

Thanks!