Abstract: A modem monitor for monitoring full duplex communications comprises one receiver for each data stream and an echo canceler for canceling "far" echo. Prior to each receiver decoding the data stream it is designed to monitor, it replicates an echo expected to be found in its received data stream from a sample of each of the other predecoded data streams. The echo canceler then subtracts the expected echo from the received data stream to remove all far echoes caused by the other data streams. The echo canceled data stream is then decoded. The monitor can also include a data communications network interface and a sample rate converter operating with the PSTN for converting from the network transmission rate to the data transmission rate.

Abstract: For use with an analog communications device coupled to an analog interface of a digital telecommunications network, the analog interface having signal conversion values corresponding to an n-level symbol table, a system and method that dynamically selects a constellation of symbols from the n-level symbol table, and a modulator/demodulator ("modem") employing the system or the method. The system includes (1)a logic circuit that selects m symbols, m being less than or equal to n, from the n-level symbol table, the m symbols being a function of the signal conversion values, and (2) a transmission circuit adapted to transmit data identifying the m symbols to a remote device digitally-coupled to the digital telecommunications network, the data allowing the analog communications device and the remote device to communicate with a common symbol table dynamically adapted to the signal conversion values of the analog interface of the digital telecommunications network.

Abstract: Techniques are disclosed for providing interoperability between a first modem and a calling identity delivery on call waiting (CIDCW) service. According to an embodiment disclosed herein, a first modem is coupled to an alerting signal receiver and a communications re-establishment device. The alerting signal receiver receives an alerting signal generated in response to an incoming call from a third party line if the first modem is communicating with a second modem. The communications re-establishment device reestablishes communications between the first modem and the second modem after the alerting signal receiver receives an alerting signal. The first modem is equipped to receive the alerting signal and reestablish communications with the second modem independent of the specific capabilities of the second modem, so that these techniques can be utilized in conjunction with a second modem not constructed in accordance with the embodiments disclosed herein.