Direct IP Call Outside LAN with specific port

[BumbleBears]

I know how to make direct IP calls outside of LAN when forwarding the default port 5060 to an individual IP phone.

What I cannot figure out is if I have multiple phones in a LAN network and I want to call a specific one from outside of the LAN, how do I specify the port to use in the call?

Example 1:
Location A
Phone 1 (WAN IP 1.2.3.4)

Location B
Phone 2 (WAN IP 1.2.3.5 Port 5061 )
Phone 3 (WAN IP 1.2.3.5 Port 5062 )

If I want to call from Phone 1 to Phone 2, I can do this by dialing 1*2*3*5 IF the router at location B is forwarding port 5060 to Phone 2 port 5061.

But, this is unrealistic, as lots of people have more than one phone at a location. So how do I include a specific port in my direct IP call? So I can dial Phone 2 or Phone 3 from Phone 1.

Thank you!