Welcome to the RingCentral Community

Sounds like you are looking at a 'Multi site' configuraton, but it could be done with Call Queues as well.

You wouldnt need two extensions on one phone - just the IVR to direct the caller to which department/function.
In the Call queue set up - there's an option to change the CallerID to the incoming type/number/quque name - so you'd see which path the caller has taken to reach you.

Each incoming phone number can be set to go to a specific IVR / call queue

it's a bit hidden, but you can make Custom rules/routing from the IVR

If you set up the RC account as a Single Site - I will say that you should make a hard copy of all the settings - they don't tell you to set up as a Multi-site, and changing over from Single/Multi will wipe out your IVR settings.

That sound like what you were asking?