Abstract: A system and method is discloded for training echo cancelers during a training sequence of a data connection between a first modern connected to a cellular cordeless phone and a second modem, wherein the cellular cordless phone in operating a microcellular mode as opposed to a cellular mode. In such circumstances, where an intermittent two-wire channel interconnects the microcell base station and a central office associated with the public switched telephone network (PSTN), an offset echo will occur in the remote echo of the second modem and the local echo of the first modem. The offset echoes can be attributed to a radio frequency (RF) delay between the cellular cordless phone and the microcell base station. The first modem can make accommodations for the RF delay by increasing the delay time utilized in setting its near-end echo canceler.

Abstract: A channel routing manager that is employed by a mobile telecommunications switching office routes voice and data calls over a carrier facility interconnecting a cell site transceiver to the mobile cellular switch and includes first and second channels that utilizes first and second encoding methods, respectively. The channel routing manager comprises a hunt group mechanism including first and second channels, wherein the first channels are sorted together and the second channels are sorted together. In addition, the channel routing manager comprises a control mechanism for routing the voice calls to one of the first channels unless all of the first channels are busy and then routing the voice calls to one of the second channels, and for routing the data calls to one of the second channels unless all of the second channels are busy and then routing the data calls to one of the first channels.

Abstract: A Mobile Switching Center (MSC) includes a cellular modem pool that comprises a number of pairs of modems in which the data terminal equipment (DTE) ports of each modem pair are cross-connected in a "back-to-back" fashion. This allows the two modems of each pair to interchange data via their DTE ports and thereby isolate that portion of a cellular fax call over the cellular communications channel from that portion of the cellular fax call through the PSTN. Fax information is transmitted over the PSTN-portion of the cellular fax call using a "1-D" fax compression scheme. However, fax information is transmitted over the cellular-portion of the cellular fax call using a "2-D" fax compression scheme and a data modulation as specified in AT&T Paradyne's "Enhanced Throughput Cellular" (ETC) Protocol. The fax terminal equipment at the cellular end of the cellular fax call is configured to perform fax compression/decompression using the "2-D" fax compression scheme.

Abstract: A system and method for establishing a link layer connection between a calling modem having a plurality of possible first physical layer modulations and one or more possible link layer connections and an answering modem having a plurality of possible second physical layer modulations and one or more possible link layer connections comprising the steps of establishing a physical layer connection between the calling and the answering modems, wherein the physical layer connection is based on a negotiated physical layer modulation chosen from the first and second physical layer modulations, and establishing link layer connection based upon said negotiated physical layer modulation. The link layer connection includes parameters that are preset to default values based upon the negotiated physical layer connection. Thus, the modems are able to avoid the link layer negotiation, thereby providing a faster and more robust connection.

Abstract: A far-end modem transmits a "pilot tone" during the time that a near-end modem is training its echo canceler. Correspondingly, the near-end modem is modified to notch, or filter, out this pilot tone from the received signal. The filtered received signal is then used by the near-end modem to train its echo canceler.

Abstract: A processor of a cellular modem monitors for the presence of a residual echo signal during a full-duplex portion of a training sequence. In particular, the processor monitors an equalizer error signal during a full-duplex training phase that follows the half-duplex training phase for the echo canceler. If the processor detects a level of the error signal greater than a predefined threshold, the processor presumes the increase in the error signal is due to the presence of a residual echo signal and performs a predefined adjustment of the taps of the corresponding echo canceler of the cellular modem.

Abstract: A system is provided for automatically selecting the mode of communication between a plurality of multi-mode modems. A calling modem and an answering modem are disposed for intercommunication across an established communication link of a telephone network. The calling modem transmits a continuous calling signal across the established link, and the answering modem detects the calling signal and analyzes the calling signal to determine the configuration of the calling modem. In response, the answering modem generates and transmits an answering signal across the established link. The calling modem detects and analyzes the answering signal to determine the configuration of the answering modem. Finally, the system determines whether the established link passes through a PSTN, and if so, transmits a 2100 hertz tone across the established link. Otherwise, the system proceeds directly to the a modem training sequence.

Abstract: A cellular data gateway situated at a mobile telecommunications switching office (MSC) is provided for interconnecting an originating mobile modem of an analog cellular system to an answer modem of a public switched telephone network (PSTN) when one of the either the cellular side or the PSTN side of the connection is capable of a fast connection sequence. The cellular data gateway comprises a quick connect cellular modem connected to the MSC and configured for interfacing with the originating mobile modem. The cellular data gateway further includes a PSTN modem connected to the MSC and configured for interfacing with the answer modem of the PSTN. The cellular modem and the PSTN modem are interconnecting in the cellular data gateway as a back-to-back modem pair. As an important part of the invention, the cellular modem includes a mechanism for delaying the initiation of a fast connect sequence with the originating mobile modem until the PSTN modem has established a connection with the answer PSTN modem.

Abstract: A cellular modem is configured in one of two modes of fax operation: a standard fax mode or an extended fax mode. In the standard fax mode, the cellular modem completes calls as in the prior art. In the extended fax mode, fax information is transmitted over a cellular-portion of the cellular fax call using a "2-D" fax compression scheme and a data modulation as specified in AT&T Paradyne's "Enhanced Throughput Cellular (ETC) Protocol". In this mode of operation, "AT-commands" related to establishing the fax connection are transmitted from the cellular modem to a Mobile Switching Center (MSC) that includes a cellular modem pool. This allows fax-capable terminal equipment at the mobile end of the connection to communicate directly with a far-end fax-capable modem in the MSC notwithstanding the presence of an analog modem at the mobile end.

Abstract: A system having an improved startup sequence for connecting two communicating modems, wherein the system includes a calling modem and an answer modem for communicating across an established communication link. Preferably, the system uses V.34 modulation protocol for information transfer after startup. In accordance with one aspect of the invention, an improved startup method includes the step of transmitting a unique calling signal from the calling modem, wherein the calling signal identifies the configuration of the calling modem. The modem "configuration" includes information relating to the communication capabilities of the modem, as well as information relating to the physical interconnection (or communication link) of the modem. The method further includes the step of transmitting a unique answer signal from the answer modem to the calling modem, wherein the answer signal identifies the configuration of the answer modem.

Abstract: A modem dynamically selects the type of error-control negotiation sequence as a function of a negotiated parameter of the physical layer. In one embodiment of the invention, a modem selects between error-control negotiation sequences as a function of the type of modulation negotiated in the physical layer. In particular, the modem has at least two type of error-control negotiation sequences to select from: "LAPM or Disconnect," and "LAPM, MNP or Buffer." When the modem negotiates a V.32 or higher modulation, the modem uses the "LAPM or Disconnect" error control negotiation sequence. However, when the modem negotiates a V.22 bis or lower modulation, the modem uses the "LAPM, MNP or Buffer" error control sequence.

Abstract: An new cellular interface directly couples the speaker and microphone of a cellular telephone to a simultaneous voice and data (SVD) modem. This interface allows a cellular telephone user to use their cellular telephone for simultaneous voice and data communications over the cellular network. In addition, of the SVD modem has a port coupled to a switched facility of a switching system, this cellular interface allows the cellular telephone user to place a telephone call from their cellular telephone over the switched facility.