The goal of the entire project is to provide office services like facsimile, email, phone and Microsoft Office inside of Local Area Networks. This part enables the users to transmit voice data over Internet Protocol from one terminal to another.

The ITU-Recommendation H.323 describes terminals, equipment, and services for multimedia communication over LAN which do not provide a guaranteed quality of service. Based on this recommendation and a basic introduction given by Siemens Switzerland Inc. we designed a voice terminal and the gatekeeper.

The voice terminal is a simple but useful computer endpoint, based on a Java application, which allows the developer to take notice of action inside the H.323 stack from RADVision. Actually it can build a connection to another voice terminal, to Netscape Conference or the gatekeeper, implemented by another team (see voice over IP: Gateway).

One of the gatekeeper tasks is to provide the address translation, i.e. from a given phone number to the actual IP address, where the user the terminal looked for is logged in. The necessary database is accessed with LDAP, the Lightweight Directory Access Protocol which enables various requests on public directory services on Internet. That is the point where we succeeded. We have now a well working client to test the access on a LDAP server. It provides several detailed pieces of information during a request, which will be useful in future work.

All in all we got some quite good results, or at least, important basics for future study. With this project we can demonstrate that this university produces more than simple programmers after their four years of study. Our engineering was based on serious work connected with long working days thanks to the high level of motivation througout our project.

The goal of this work was to develop a fax solution which makes it possible for a company that every employee can have fax at his desk. The only condition is that the company has an Intranet and every employee who is allowed to receive and send faxes has access to the email system.

Faxes should be handled exactly like emails. It should be possible to send and receive them with every email client.

This was our starting point. We analyzed the problem and decided to write two gateways and to develop further an existing viewer which can show faxes.One gateway receives all incoming faxes. On the basis of the chosen fax number it decides which employee the fax must be sent to. It converts the fax to an email attachment and sends it to the receiver. Now the receiver can click on the attachment upon which the external viewer starts and shows the fax.

The second gateway is responsible for sending faxes. To send a fax, the user just enters a fax number instead of an email-address. As in normal use, it is possible to attach different files to the mail. This mail is now sent to the gateway. It analyzes the mail and forwards normal mails to the mailserver of the company.

Mails that must be sent to a fax number are filtered out. The gateway starts the according application for every attachment and prints the attachment. For that, it uses a special printer driver we developed. This driver builds a special file which can be sent to the destination fax machine by using the ISDN card.

We made very good progress and were able to build a running prototype for both gateways. They are implemented as Windows NT services, so they are running completely in the background. With a small program in the Control Panel they can be configured.

We were able to make some decisive improvements with the viewer. We implemented some new functions, and especially we improved the speed by about factor twelve.

Office Services Provider (OSP) should provide network services for telecommunications such as telephone, tele-facsimile, e-mail, and the use of Microsoft Office software. The H.323 Protocol will be used for Intranet IP communication. Access to the public switched telephone network (PSTN) will be offered through a Capi 2.0 driver on an ISDN card. This diploma assignment focusses onThe H.323/PSTN-Gateway. Access to PSTN through Capi had already been provided. Our assignment included building the connection between Capi and the H.323. For the PSTN we developed an answering service which converts and transmits messages to e-mail. We had to develop a simple Gatekeeper as the one that will be finally used in this project was being developed at the same time by another group.

The assignment of our part of the project consisted of not only the development of the Gateway but also of testing and performance optimization.

We tested the transmitted voice quality, the network load and the delay time as a function of the transmitted frame size using various Computers (486, P66, P133, P200 ) and terminals (Netscape Conference, FirstCall, Java-Terminal).

The present development stage of the Gateway allows prototype usage. The Gateway transmits multiple connections.

This diploma-work has acquired the basic know-how which is necessary to connect small companies to the TWI network by a broadband line.

The idea is that the customer doesn't have to take care of the technical details. The TWI will give the company a small computer, which manages the broadband connection between the LAN of the company and the TWI network. Also the computer takes on the job of the proxy- and www-server. The computer itself is as small as possible and allows the customer only to connect his LAN to this computer. All of the configurations are made by the TWI.

The computer should run with a small Windows NT (Embedded NT). A special developer software was used to create such small operating systems. It was possible to generate embedded NT, which needs only half of the memory space.The technology used for the broadband connection between the customer and the TWI is HDSL (High-bit-rate Digital Subscriber Line). This new technology allows to transfer 768 kbps with ordinary telephone lines. The distance varies between 4 km up to 7 km (depending on the wire gauge).

At the end of the diplomawork there was a test network available with the same conditions as there would be at the real network. It was possible to browse in the internet with a computer in the customer LAN, connected by the HDSL line.Additionally embedded NT operating systems have been created which will be a good basis for further developments.

The know-how of this work can be used in a later realisation of such network projects at the TWI. Or it can be used as an exhibit to show this topic to interested providers who want to realise such networks.