The project "Teleteaching Service for the Greek PTT" aims to develop one commercial Teleteaching application and comprises the continuation of the Pilot Teleteaching project, which the CTI and the Greek PTT have completed. More particularly the project "Teleteaching Service for Greek PTT" aims at the following: · Implementation of an application for high quality synchronous Teleteaching over IP and ISDN networks (with the use of one BRI connection) with the use of special hardware. Implementation of an application for high quality synchronous Teleteaching over IP and ISDN networks (with the use of three BRI connections) with the use of special hardware. · Implementation of an application for high quality synchronous Teleteaching over IP and ISDN networks (with the use one BRI connection) without the use of special hardware. In this project, the CTI and the Greek PTT are the only participants and the role of the CTI is the design and the implementation of the applications above.