AT Commands F-77
Register Descriptions
NOTE
If :T2 is set to 0, V.23 half-duplex connections are not attempted. The modem
attempts to establish a connection for the length of time specified by register S7
before hanging up.
:T3=
n Timer for V.21 and V.23 Answer Tone Duration
Range:
Where n is an integer from 0 to 33 representing tenths of a second.
Default:
33 (3.3 seconds)
This command requires either V.21 operation (%F0 is set and the modem speed is 300
bps) or V.23 operation (%Fn, where n=1, 2, or 3).
When the answering modem is set for V.21 or V.23 operation, :T3 determines the
duration of the V.25 answer tone that is sent to the originating modem. When :T3 is set
to 0, no answer tone is sent. All V.21 and V.23 answers begin with two seconds of
silence unless :T3 is set to 0.
When the originating modem is set for V.21 or V.23 operation, :T3 determines how
long the modem waits after detecting answer tone before proceeding with the
connection. When :T3 is set to 0, the originating modem does not wait for answer tone.
:T4=
n Timer for Line Turnaround Delay - Carrier On
Range:
Where n is an integer from 0 to 255 (in increments of 12.5 milliseconds).
Default:
20 (250 milliseconds)
This command takes effect only during normal mode V.23 half-duplex connections.
After the modem turns the carrier off, this command determines the minimum time the
modem waits for the remote modem to respond before turning carrier back on again to
resume sending data.
:T5=
n Timer for V.23 Half-Duplex Intercharacter Delay
Range:
Where n is an integer from 0 to 255 (in increments of 12.5 milliseconds).
Default:
7 (87.5 milliseconds)
This command takes effect only during normal mode V.23 half-duplex connections.
Sets the length of time the modem waits after transmitting the last data character in the
transmit buffer before turning carrier off. :T5 may need to be adjusted if the local
computer intercharacter time causes excessive line turnarounds.
