Asterisk for multiple virtual PBX system


I am new to Asterisk, and we are looking at it as a solution to allow a virtual office system for several users at once.
The setup would be that each user has their own phone number but all phone numbers go to the same incoming line.
I was looking through the Asterisk documentation and I didn’t see an easy way of doing the following:
Setting up a system whereby the person calling is directed to a different extension or menu based on the number that they dialed, given that there are several numbers that go to the same line.
Does anyone out there know of a fast solution for this using the existing scripts that Asterisk uses or would we end up having to develop a custom module using an API to accomplish this.
Is there a variable in the configuration scripting that corresponds to what number you dialed?

Thank you