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 variable-length 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 I 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
Verifying Voice Ports
After physically connecting analog or digital devices to a Cisco voice-enabled router, you might need to issue show, test, or debug commands to verify or troubleshoot your configuration. For example, the following list enumerates six steps to monitor and trou-bleshoot voice ports:
Step 1. Pick up the handset of an attached telephony device and check for a dial tone. If there is no dial tone, check the following:
■ Is the plug firmly seated?
■ Is the voice port enabled?
■ Is the voice port recognized by the Cisco IOS?
■ Is the router running the correct version of Cisco IOS in order to recognize the module?
■ Is a dial peer configured for that port?
Step 2. If you have a dial tone, check for DTMF voice band tones, such as touch-tone detection. If the dial tone stops when you dial a digit, the voice port is probably configured properly.
Step 3. Use the show voice port command to verify that the data configured is correct. If you have trouble connecting a call, and you suspect that the problem is associated with voice-port configuration, you can try to resolve the problem by performing steps 4 through 6.
Step 4. Use the show voice port command to make sure the port is enabled. If the port is administratively down, use the no shutdown command. If the port was working previously and is not working now, it is possible the port is in a hung state. Use the shutdown/no shutdown command sequence to reinitialize the port.
Step 5. If you have configured E&M interfaces, make sure the values associated with your specific PBX setup are correct. Specifically, check for two-wire or four-wire wink-start, immediate-start, or delay-start signaling types, and the E&M interface type. These parameters need to match those set on the PBX for the interface to communicate properly.
Step 6. You must confirm that the voice network module (VNM) (that is, the module in the router that contains the voice ports) is correctly installed. With the device powered down, remove the VNM and reinsert it to verify the installation. If the device has other slots available, try inserting the VNM into another slot to isolate the problem. Similarly, you must move the voice interface card (VIC) to another VIC slot to determine whether the problem is with the VIC card or with the module slot.
For your reference, Table 3-6 lists six show commands for verifying the voice-port configuration.
Table 3-6 Commands to Verify Voice Ports
|
Command |
Description |
|
show voice port |
Shows all voice-port configurations in detail |
|
show voice port slot/subunit/port |
Shows one voice-port configuration in detail |
|
show voice port summary |
Shows all voice-port configurations in brief |
|
show voice busyout |
Shows all ports configured as busyout |
|
show voice dsp |
Shows status of all DSPs |
|
show controller T1 | E1 |
Shows the operational status of a controller |
Example 3-7 provides sample output for the show voice port command.
Example 3-7 show voice port Command
Example 3-8 provides sample output for the show voice port summary command.
Example 3-8 show voice port summary Command
For your further reference, Table 3-7 provides a series of commands used to test Cisco voice ports. The test commands provide the capability to analyze and troubleshoot voice ports on voice-enabled routers. As Table 3-7 shows, you can use five test commands to force voice ports into specific states to test the voice port configuration. The csim start dial-string command simulates a call to any end station for testing purposes.
Table 3-7 test Commands
|
Command |
Description |
|
test voice port port_or_DS0-group_identifier detector {m-lead | battery-reversal | ring | tip-ground | ring-ground | ring-trip} {on | off | disable} |
Forces a detector into specific states for testing. |
|
test voice port port_or_DS0-group_identifier inject-tone {local I network} {1000hz I 2000hzI200hzI3000hzI300hzI3200hz I 3400hz I 500hz I quiet I disable} |
Injects a test tone into a voice port. A call must be established on the voice port under test. When you are finished testing, be sure to use the disable option to end the test tone. |
|
test voice port port_or_DS0-group_identifier loopback {local I network I disable} |
Performs loopback testing on a voice port. A call must be established on the voice port under test. When you finish the loopback testing, be sure to use the disable option to end the forced loopback. |
|
test voice port port_or_DS0-group_identifier relay {e-lead I loop I ring-ground I battery-reversal I power-denial I ring I tip-ground} {on I off I disable} |
Tests relay-related functions on a voice port. |
|
test voice port port_or_DS0-group_identifier switch {fax I disable} |
Forces a voice port into fax or voice mode for testing. If the voice port does not detect fax data, the voice port remains in fax mode for 30 seconds and then reverts automatically to voice mode. After you enter the test voice port switch fax command, you can use the show voice call command to check whether the voice port is able to operate in fax mode. |
|
csim start dial-string |
Simulates a call to the specified dial string. This command is most useful when testing dial plans. |
