A lot of small genuine companies use these services. I had a desk is one of these places in the UK for a while. They have a phone system in place where the name of the business being called flashes up so the secretary knows which name to answer it under. They just take a message and say 'they're all in a meeting right now' etc etc. The same secretary might answer calls for 40 or 50 businesses. There are different packages, some will forward mail as well and some provide hot desks and normal office space.