To any route that has a "Configured", "Named" IPortal ... on your PC ... to another PC in your house ... or to the friend down the street ... or worldwide ... as long as they have the same assets downloaded, in the sent consist.
I believe that you also have to make an: "Allowable Program Excption Rule" to your Antivirus Progam to "Allow" your Trainz version: Launcher, CM (CMP), and possibly another Trainz file through ... I just read in a TS12 IPortal thread.
Iportals can not (at this time)be used to sent trains to another person via the internet With TS12.
You can send trains to another route on your computor.