ITU/TDD modem

A modem system that can communicate with a remote device that includes a carrier based negotiating modem or a modem that uses a carrierless protocol, wherein the negotiating modem is a modem that makes a connection through a handshaking procedure that includes a negotiation phase, the modem system comprising:

• at least one conductor through which signals related to an incoming call pass;
• and
• processing circuitry connected to the at least one conductor, and in response to the incoming call, the processing circuitry conducts a carrier based connection attempt procedure with respect to the remote device during a first length of time controlled by a value stored in the processing circuits, during which the processing circuitry attempts to make a carrier based connection with the remote device, and during at least a portion of the carrier based connection attempt procedure, the processing circuitry emits answer tone signals, and
• (a) if no carrier based response signals from the remote device is received by the processing circuitry during the first length of time, the processing circuitry enters a carrierless mode of communications and sends data according to the carrierless protocol, and
• (b) if a carrier based response signal from the remote device is received by the processing circuitry during the first length of time, the processing circuitry continues the connection attempt procedure for a maximum of a second length of time set by the processing circuitry through extending the length of time provided by the value stored in the processing circuitry.

A modem system that can communicate with a remote device that includes a carrier based negotiating modem or a device that uses a carrierless protocol, wherein the negotiating modem is a modem that makes a connection through a handshaking procedure that includes a negotiation phase, the modem system comprising:

• at least one conductor through which signals related to an incoming call pass;
• and
• processing circuitry connected to the at least one conductor, and in response to the incoming call, the processing circuitry conducts a carrier based connection attempt procedure with respect to the remote device during a first length of time controlled by a value stored in the processing circuitry, during which the processing circuitry attempts to make a carrier based connection with the remote device, and
• (a) if no carrier based response signal from the remote device is received by the processing circuitry during the first length of time, the processing circuitry enters a carrierless mode of communications and emits tones according to the carrierless protocol, and
• (b) if a carrier response signal from the remote device is received by the processing circuitry during the first length of time, the processing circuitry continues the carrier based connection attempt procedure during the negotiation phase.