Hissing/static on Grandstream GXP2100 phones

I have a new system running Distro 3.211.63-10 using new Grandstream GXP2100 phones. When users do a 2 way intercom using the speaker phone on both sides of the call there is a sort of hissing/static that pulsates over the speaker. I do not hear the hissing on the handset. Has anyone experienced this issue?

I am beginning to think that the speaker phones are just picking up ambient noise from the room.