Survey of Digital PBX Design

It is the purpose of this paper to discuss the capabilities and organization of all digital PBX's currently being manufactured in the United States. A digital PBX is one which encodes incoming signals into representations where the presence, or absense, of pulses, or levels, defines the signal; such a system switches signals by routing, multiplexing, or storing these pulses or levels. Pulse amplitude and pulse width modulation systems are thus excluded from this discussion.