1. A system comprising: a proxy server to receive and store a first table for address translation and registration of plural terminals associated therewith, each terminal being capable of participating in a telephone call to be implemented over a packet switching data network, said proxy server being connected to a data network; and a pass through server connected to said data network and through which information between said proxy server and any of said terminals passes, said pass through server including a second table that mirrors said first table, said pass through server also being configured to communicate information to and from an applications computer, said applications computer including software to at least control or monitor calls among said terminals over said data network, said applications computer and said pass through server exchanging information in a manner that translates a virtual number received from a calling party to one or more physical numbers representing called parties.