We have one line coming in to the building and the group wants to have the ability to route incoming calls to different people. I think that means incoming calls would be forwarded to different phone numbers. ?
Just as an FYI, if you only have one phone line coming into the building, then forwarding externally is not possible. You will need at least 2 call paths for every call that is getting forwarded off site, one coming in and a second going out.
Basically Grasshopper appears to be just a Auto Attendant in the cloud.It would answer the call first then direct callers to another phone number. This might make sense in your situation. I don't know if I would call it a PBX. You still would not be replacing your internal office equipment.
There are a lot of other VoIP services that would do the same thing as Grasshopper, such as Ring Central, Vonage, Nextiva, etc. Most of the other services also offer VoIP to the desktop, which can start to add up in cost if where to replace all your internal handsets. If all that you need is a cloud Auto Attendant, then maybe Grasshopper is a good choice because it looks like that is primarily what they do.
In order for these services to work you would have to "port" over your local number to the service so that the VoIP service can answer the call first. You may need to change the local incoming phone number if that is the number that people call. This could take some time and coordination with your local service provider so that you don't miss any calls.
