Abstract: A facsimile apparatus includes a user interface operative to facilitate communications between the apparatus and at least one user application in operative communication with the apparatus, a network interface operative to facilitate communications between the apparatus and an analog communications network and an IP communications network. The apparatus further includes a controller connected to the user interface and network interface. The controller is operative in a first mode to communicate with the analog communications network using a first facsimile protocol and being operative in at least a second mode to communicate with the IP communications network using the first facsimile protocol and a voice band data protocol.

Abstract: A buffer memory is provided that comprises a plurality of memory elements for storing data elements in an order of arrival, wherein the plurality of memory elements have a variable size and wherein each memory element comprises a pointer (such as a next block starting index) to a memory element storing a next data element. Additionally, each memory element optionally further comprises a block size field indicating the variable size and/or a sequence number field indicating a sequence number of the corresponding data element. The buffer memory optionally comprises a largest sequence variable to store a sequence number of a data element in the buffer memory having a largest sequence number. The largest sequence variable is updated if a newly arrived data element has a sequence number that is larger than the largest sequence variable. A method is also provided for managing the disclosed buffer memories.

Abstract: Described embodiments provide an IP-aware modem, such as for use in an IP-aware facsimile machine, operable with an IP packet network. The IP-aware modem has voice-band data engine that receives packets from the packet network, converts data in the packets to PCM samples, stores the samples as PCM sample frames in a buffer for further processing by the modem, and determines for each PCM sample frame whether or not during the conversion one or more packets were missing. An equalizer or timing recovery element in the modem adapts using the PCM sample frames and suspends the adaptation for the time period of each PCM sample frame converted without the one or more missing packets. Similarly, searches of the PCM sample frames for certain modem synchronization signals are skipped when, during the search, the searched PCM sample frame was converted without the one or more missing packets.

Abstract: Described embodiments provide an IP-aware modem, such as for use in an IP-aware facsimile machine, operable with an IP packet network. The IP-aware modem has voice-band data engine that receives packets from the packet network, converts data in the packets to PCM samples, stores the samples as PCM sample frames in a buffer for further processing by the modem, and determines for each PCM sample frame whether or not during the conversion one or more packets were missing. An equalizer or timing recovery element in the modem adapts using the PCM sample frames and suspends the adaptation for the time period of each PCM sample frame converted without the one or more missing packets. Similarly, searches of the PCM sample frames for certain modem synchronization signals are skipped when, during the search, the searched PCM sample frame was converted without the one or more missing packets.

Abstract: A facsimile apparatus includes a user interface operative to facilitate communications between the apparatus and at least one user application in operative communication with the apparatus, a network interface operative to facilitate communications between the apparatus and an analog communications network and an IP communications network. The apparatus further includes a controller connected to the user interface and network interface. The controller is operative in a first mode to communicate with the analog communications network using a first facsimile protocol and being operative in at least a second mode to communicate with the IP communications network using the first facsimile protocol and a voice band data protocol.

Abstract: A method for correcting at least one error in a data transmission over a packet-based communication network includes the steps of: generating a sequence of data packets for transmission over the packet-based communication network, the sequence of data packets being arranged into a plurality of packet frames, each of at least a subset of the packet frames including at least a primary data packet and a number of redundant data packets which is a function of a prescribed redundancy pattern, the subset of packet frames having a non-uniform distribution of redundant data packets therein; transmitting the sequence of data packets over the communication network; and recovering at least one missing data packet in the sequence of data packets using at least one corresponding redundant data packet in at least one subsequently received packet frame when the missing data packet is identified in a receiver of the sequence of data packets.

Abstract: A method for correcting at least one error in a data transmission over a packet-based communication network includes the steps of: generating a sequence of data packets for transmission over the packet-based communication network, the sequence of data packets being arranged into a plurality of packet frames, each of at least a subset of the packet frames including at least a primary data packet and a number of redundant data packets which is a function of a prescribed redundancy pattern, the subset of packet frames having a non-uniform distribution of redundant data packets therein; transmitting the sequence of data packets over the communication network; and recovering at least one missing data packet in the sequence of data packets using at least one corresponding redundant data packet in at least one subsequently received packet frame when the missing data packet is identified in a receiver of the sequence of data packets.

Abstract: A method for correcting at least one error in a facsimile transmission over a packet switched communications network includes the steps of: detecting, by a first gateway coupled to the communications network, at least one missing data packet in a sequence of data packets transmitted from a second gateway coupled to the communications network during the facsimile transmission; transmitting, from the first gateway, a request for retransmission of the missing data packet to the second gateway; determining whether the missing data packet is available for retransmission; and, when the missing data packet is available, retransmitting the missing data packet to the first gateway.

Abstract: A facsimile apparatus includes a user interface operative to facilitate communications between the apparatus and at least one user application in operative communication with the apparatus, and a network interface operative to facilitate communications between the apparatus and at least one of a plurality of communications networks coupled to the apparatus. The apparatus further includes a controller connected to the user interface and network interface. The controller is operative in a first mode to communicate with a first one of the communications networks using a first protocol and is operative in at least a second mode to communicate with a second one of the communications networks using a second protocol.

Abstract: A buffer memory is provided that comprises a plurality of memory elements for storing data elements in an order of arrival, wherein the plurality of memory elements have a variable size and wherein each memory element comprises a pointer (such as a next block starting index) to a memory element storing a next data element. Additionally, each memory element optionally further comprises a block size field indicating the variable size and/or a sequence number field indicating a sequence number of the corresponding data element. The buffer memory optionally comprises a largest sequence variable to store a sequence number of a data element in the buffer memory having a largest sequence number. The largest sequence variable is updated if a newly arrived data element has a sequence number that is larger than the largest sequence variable. A method is also provided for managing the disclosed buffer memories.

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: A method is presented to enable high speed transmission in the upstream channel from a customer's modem to a PCM modem connected to the public switched digital network. The upstream channel is equalized by having the client modem send a known training sequence in the upstream direction to the server modem. The server modem calculates the cross-correlation between the known training sequence and the sequence as actually received from the client modem. The cross-correlation is then multiplied by the known auto-correlation of the training sequence to produce a model of the channel response. The channel response is then reported to the client modem so that it may adjust its pre-equalizer to construct the signal that the client modem will thereafter send in the upstream direction.

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.