The objective of this thesis is to present a useful application for the Integrated Services Digital Network (ISDN) that is expected to one day replace the analog phone system in use today. ISDN itself and its continuing evolution are detailed. The system developed as a part of this thesis involved the creation of an inexpensive "phone terminal" that can serve as an ISDN terminal and also as a bridge to a Local Area Network (LAN). The "phone terminal" provides a hybrid electronic mail system that allows the attachment of speech to text within a message. Messages created with this "phone terminal" could theoretically be sent locally using the LAN interface and globally using ISDN to other users with either "phone terminals" or multimedia personal computers. For this project, the two "phone terminals" created were interconnected via an Ethernet and using an 80486 PC to act as a Central Office System. This Central Office System provides speech/message storage for the "phone terminals." It makes use of speech compression techniques to minimize the storage requirements. The speech compression techniques used as well as the field of speech coding in general are discussed.
Library of Congress Subject Headings
Integrated services digital networks; Electronic mail systems; Voice mail systems
Department, Program, or Center
Computer Engineering (KGCOE)
McBride, Andrew, "A Hybrid voice/text electronic mail system: an application of the integrated services digital network" (1994). Thesis. Rochester Institute of Technology. Accessed from
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