Privacy booths and pods
If the real complaint in your office is people taking calls at their desks, this is the category that solves it. Booths contain noise at source, which no amount of screening between desks can do.
Cheaper than treating a floor
Two or three booths usually cost less than acoustically treating a whole open-plan area, and they solve the specific problem rather than lowering the general noise level a little.
What to check
Ventilation and lighting, which decide whether people will actually sit in one for half an hour. Also check whether it needs a power feed and how it will get there, since that constrains where it can stand more than the footprint does.
For open-plan noise generally, see acoustic solutions.
What to check
Ventilation, lighting and how power reaches the unit, since that constrains where it can stand more than the footprint does. Booths solve call noise better than any amount of screening, and pair well with soft seating in the same breakout area.