At the office we use the usual Polycom conference devices.
As to multimedia, since that's another use I'd get some nice speaker set. Right now I have this pair of Satechi's. Nice stuff. https://www.amazon.com/gp/product/B00GMREIKS/
Hi Experts
Which is currently the affordable best quality loud and clear speaker phone for conference call and best Multimedia (Speaker, music and camera) and battery capability phone available.
Regards
P

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