Abstract: An enhanced telephony call waiting feature is provided wherein identifying information related to a third party wishing to converse with a first party already engaged in a conversation with a second party is spontaneously provided to the first party. The method comprises the steps of the local office sending a call waiting tone having predetermined characteristics to the first party and its apparatus responding thereto by muting its associated handset for a predetermined interval of time. The local office then transmits the identification data relating to the third party and the first party apparatus receives and displays to the first party the identification information related to the third party thereby allowing the first party to either accept or reject the waiting call in the conventional manner but also based on the displayed information.

Abstract: A synchronous optical transmission system for interfacing SONET formatted channels to lower speed channels in either a SONET format or otherwise. The transmission system incorporates a fiber transmission system, terminal multiplexers and add/drop multiplexers that in turn incorporate a plurality of features, such as parallel scrambling circuitry, frame synchronization circuitry and the like.

Abstract: The present invention relates to a baseband transmitter using a precision voltage reference and field effect transistor switches in an arrangement such that output amplitude variations due to power supply and transistor "on" voltage variations are virtually eliminated. The present invention results in a transmitter suitable for the generation of transmit signals conforming to different rate and/or frequency constraints. The data rate and output pulse characteristics of the transmitter are selected by a single 1-of-N switch selection. A common amplifier is provided for different data rates.

Abstract: The present invention consists of a multirate data receiver which will recover data at any of N data rates with no predetermined restrictions on the value of N. The data rate at which the receiver operates is selected by a single 1-of-N switch selection. An equalizer section is constructed for each of the N data rates but are all controlled by the same (common) automatic adjustment circuitry, which controls gain and frequency compensation. The output from one of the equalizer sections is selected by an analog multiplexer constructed of field effect transistor (FET) switch circuits. The recovered waveforms from the equalizer sections are processed by common circuitry to recover the transmitted data. Clock recovery may be accomplished, for example, by a digital phase locked loop constructed such that the characteristics of the loop filters and divide-by-M feedback counters are easily modified by logical signals controlled by the 1-of-N switches.