The Voice Synthesizer and Telephone Program are a set of programs installed on the Supercomputer. The telephone program is used fairly frequently. It is used almost every time the Factory Interface operator, usually Jeremie Belpois or Aelita Schaeffer, calls someone. Whenever someone with a profile within the Supercomputer is called up, their Lyoko ID Card is shown beside the program's window. If an unknown person is called up, the program just shows the default card. The Voice Synthesizer is also integrated into the program, so that a different voice comes out at the other end if needed. It is unknown who wrote it.
The appearance of the program changed about halfway through season 2, from the old look which had a phone emulator and falling matrix letters, to a new GUI which had a phone emulator and the Lyoko ID cards. By looking at the phone numbers displayed in the program's window, you can see that the dialing code for France is 33.
The Voice Synthesizer is a program integrated into the Telephone Program. It allows the user to imitate any voice programmed into it. This was first introduced in "Saint Valentine's Day" to impersonate Jean Pierre Delmas. It was used on a few other occasions, such as in "Double Take", to impersonate James Dunbar.