The only case I can think of that matters is support/sales calls. If their phone staff does not have dedicated office space at home, it's a bit hard to organise. You can have at least small dividers in the office so that the background noise you hear over the phone is other calls, mostly quiet. I think it would be a different experience if I was handling incoming calls - even with a dedicated office room, I'd get anything like a bus passing by, lawnmowers, cats screaming to go out, rain on metal roof, etc.