Traditionally, telephony supplementary services are implemented using a centralized approach for which a public switch or a private branch exchange (PBX) plays a crucial role in the implementation. With advancements in personal computer, networking, and digital signal processing technologies, an alternative approach is now possible. This
approach exploits the power of the workstation (or end system) and allows the implementation of basic telephony services (i.e., call establishment and termination) and supplementary services (e.g., call transfer, call deflection, and camp-on busy) without requiring the switch to support any specific features. The network is only required to provide two types of end-to-end connection, realtime and non-realtime. Any signaling required is accomplished by control
information sent over a peer-to-peer signaling channel between end systems. Encoded voice samples are exchanged over another peer-to-peer voice channel. This end-system-oriented approach offers advantages
such as scalability, potentially faster introduction of new supplementary services, and the elimination of some centralized functions. Using a reference architecture, this paper describes the signaling messages required and the details of how the basic and some supplementary services can be implemented.
By: M. Graf, H.L. Truong, and J.W. Wong
Published in: RZ2920 in 1997
LIMITED DISTRIBUTION NOTICE:
This Research Report is available. This report has been submitted for publication outside of IBM and will probably be copyrighted if accepted for publication. It has been issued as a Research Report for early dissemination of its contents. In view of the transfer of copyright to the outside publisher, its distribution outside of IBM prior to publication should be limited to peer communications and specific requests. After outside publication, requests should be filled only by reprints or legally obtained copies of the article (e.g., payment of royalties). I have read and understand this notice and am a member of the scientific community outside or inside of IBM seeking a single copy only.
Questions about this service can be mailed to reports@us.ibm.com .