method and apparatus for effecting a voice communication between user terminals connected via a communication network include displaying a menu of country options to a user and receiving a number in local form . formatting rules are recalled for a destination country selected by the user from the country options . a country prefix for the destination country is prepended to the number in accordance with the formatting rules to generate a formatted number . the formatted number is supplied to a client installed at the user terminal for effecting the voice communication using the formatted number .