what would your pda do with a phone call? Does your pda have a mic?
concerning your question the easiest setup is to put in a vpn router like a linksys that contains vpn client software. You run the vpn software after you have made an internet connection to then connect to your network. Then you run something like RDP to connect to your pc at home.
Or you get and install any number of products to do this like logmein, hamachi, etc. Google search for them so you have a better understanding on how this works.