Timers and Timing
You can set a number of timers and timing parameters for fine-tuning a voice port.
Following are voice-port configuration mode commands you can use to a set variety of
timing parameters:
■ timeouts initial seconds: Configures the initial digit timeout value in seconds. This
value controls how long the dial tone is presented before the first digit is expected.
This timer value typically does not need to be changed.
■ timeouts interdigit seconds: Configures the number of seconds for which the system
will wait between caller-entered digits before sending the input to be assessed.
If the digits are coming from an automated device, and the dial plan is a variablelength
dial plan, you can shorten this timer so the call proceeds without having to
wait the full default of 10 seconds for the interdigit timer to expire.
■ timeouts ringing {seconds | infinity}: Configures the length of time a caller can continue
to let the telephone ring when there is no answer. You can configure this setting
to be less than the default of 180 seconds so that you do not tie up a voice port
when it is evident the call is not going to be answered.
■ timing digit milliseconds: Configures the DTMF digit signal duration for a specified
voice port. You can use this setting to fine-tune a connection to a device that
might have trouble recognizing dialed digits. If a user or device dials too quickly, the
digit might not be recognized. By changing the timing on the digit timer, you can
provide for a shorter or longer DTMF duration.
■ timing interdigit milliseconds: Configures the DTMF interdigit duration for a specified
voice port. You can change this setting to accommodate faster or slower dialing
characteristics.
■ timing hookflash-input milliseconds and hookflash-output milliseconds:
Configures the maximum duration (in milliseconds) of a hookflash indication.
Hookflash is an indication by a caller that wants to do something specific with the
call, such as transfer the call or place the call on hold. For the hookflash-input command,
if the hookflash lasts longer than the specified limit, the FXS interface
processes the indication as on-hook. If you set the value too low, the hookflash
might be interpreted as a hang-up. If you set the value too high, the handset has to
be left hung up for a longer period to clear the call. For the hookflash-output command,
the setting specifies the duration (in milliseconds) of the hookflash indication
that the gateway generates outbound. You can configure this to match the requirements
of the connected device.
Under normal use, these timers do not need to be adjusted. In two instances, these timers
can be configured to allow more or less time for a specific function:
■ When ports are connected to a device that does not properly respond to dialed digits
or hookflash
■ When the connected device provides automated dialing
Example 3-6 shows a configuration for a home for someone with a disability that might
require more time to dial digits. Notice the requirement to allow the telephone to ring,
unanswered, for 4 minutes. The configuration enables several timing parameters on a
Cisco voice-enabled router voice port 0/1/0. The initial timeout is lengthened to 15 seconds;
the interdigit timeout is lengthened to 15 seconds; the ringing timeout is set to 240
seconds; and the hookflash-in is set to 500 ms.
Example 3-6 Timers and Timing Configuration
160 Authorized Self-Study Guide: Cisco Voice over IP (CVOICE)
Router(config)#voice-port 0/1/0
Router(config-voiceport)#timeouts initial 15
Router(config-voiceport)#timeouts interdigit 15
Router(config-voiceport)#timeouts ringing 240
Router(config-voiceport)#timing hookflash-in 500