Two companies one phone system issue

So here is my dilemma I have person that is financial advisory that needs to be completed separated from are network. So my problem is i need him to receive phone calls for outbound and inbound from a different number then what the firm number has. So what do i need to do make this happen

Thank you

I suggest that for your “financial advisory” you just get him a SIP phone and another DID from your VSP, register the SIP phone directly to the VSP, Asterisk/FreePBX is not necessary in this scenario.