Black Box MD1641A, MD1640A manual Line Probe Commands, Force Answer Mode a

SERIES II INTELLIGENT DATA/FAX MODEMS

Force Answer Mode A

You can force the Series II Modem into Answer mode with the modem’s

Acommand.

Entering ATA when in Command mode immediately brings your mo- dem off-hook, out of Command mode and into On-Line Answer mode, and causes it to transmit its carrier signal over the phone line. If no responding carrier tone is received by your modem within forty-five seconds (or some other time as determined by S-Register S7), your modem stops transmitting its tone, hangs up, and goes back into Command mode.

Exiting Command Mode, Going Back On-Line O

You can bring the Series II Modem out of Command mode and back into On-Line mode by entering ATO (where O is the letter O, not the number 0). In this case, the O command reverses what was done by entering the Escape Code. The O command will bring the modem into the same On-Line mode (Originate or Answer) that it was in prior to going into Command mode.

5.4.13 Line Probe Commands

Before V.34 negotiation takes place, remote and local modems transfer their functional capabilities using modulated calling and answering tones; indicating the common capabilities of the modem at each end.

Once this is done, a probing signal is passed between the modems to identify impairments in the telephone channel (e.g., Receive Signal Strength vs. Frequency, Noise vs. Frequency and Signal to Noise Ratio vs. Frequency). After receiving the results of the probing signal, the modem receivers and transmitters begin with the lowest speed and move up until reaching the highest speed at which they can exchange data. All this occurs in about five seconds.

There are a number of Line Probe Commands. These commands are configurable and can be stored to RAM (via AT&W0).

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