We are currently testing a few SPA942 and SPA964. We have found that when someone is on speaker phone the other person can sometimes hear themselves speaking. Also there tends to be a lot of background noise and an overall 'in the can' sound(sounds echo and it sounds like you are working in a can).
I'm looking into adjusting the speakerphone input gain to address this problem. Is this the place to start? Are there other setting that can/may need to be adjusted?
Also I was wondering if the PBX has any influence of this type of thing?