The Eight-port RJ-21 FXS Module is a high-density analog phone and fax relay interface. By providing service to analog phones and fax machines, the eight Foreign Exchange Station (FXS) ports emulate a Public Switched Telephone Network (PSTN) central office (CO) or private branch exchange (PBX).
This section describes how to configure the eight-port FXS module on the Catalyst 4224. This section contains the following topics:
Eight-Port RJ-21 FXS Module User Interface Conventions
The eight-port Foreign Exchange Station (FXS) module is similar to the two-port FXS analog interface card (VIC-2FXS). Because the eight-port FXS module is located in slot 4, the eight ports are numbered 4/0 to 4/7. The front panel of this module has two rows of four LEDs each. The LEDs numbered 0 through 3 on the left side represent ports 4/0 through 4/3, and the LEDs numbered 4 through 7 on the right side represent ports 4/4 through 4/7.
Configuring FXS Voice Ports
The default values for FXS voice ports are usually adequate but this section includes information on changing the defaults if necessary. This section describes the following procedures:
To configure FXS voice ports, use the following commands in privileged EXEC mode:
Command
Purpose
configure terminal
Enters global configuration mode.
voice-portslot-number/port
Identifies the voice slot and port number you want to configure, and entesr voice port configuration mode.
signal {loop-start | ground-start}
Selects the appropriate signal type for this interface.
cptonecountry
Selects the appropriate voice call progress tone for this interface. The default for this command is us. For a list of supported countries, refer to the Voice, Video, and Home Applications Command Reference.
ring frequency{25 | 50}
Selects the appropriate ring frequency (in Hertz) specific to the equipment attached to this voice port.
connection plarstring
(Optional) Specifies the PLAR1 connection if this voice port is used for a PLAR connection. The string value is any series of digits that specifies the destination E.164 telephone number.
music-thresholdnumber
(Optional) Specifies the threshold (in decibels) for music on hold. Valid entries are from -70 to -30.
descriptionstring
(Optional) Attaches descriptive text about this voice port connection.
comfort-noise
(Optional) Specifies that background noise will be generated.
For complete information about configuration commands and about configuring LAN and WAN interfaces on your switch, refer to the Cisco IOS configuration guides and command references.
The following example shows how to use the FXS configuration commands:
Gateway# conf t
Enter configuration commands, one per line. End with CNTL/Z.
Gateway(config-voiceport)# description "Connection to PBX"
Gateway(config-voiceport)# comfort-noise
To display the values configured, use the show running-config command.
Validating the Configuration
To validate your voice port configuration, perform one or both of the following tasks:
Pick up the handset of a telephony device attached to your IP network and check for a dial tone. The corresponding LED turns green to indicate "off-hook" and "call-in-progress" conditions. If the dial tone stops when you dial a digit, then the voice port is probably configured properly.
To confirm that the data is configured correctly, use the show voice port command as follows:
Gateway# sh voice port 4/0
Foreign Exchange Station 4/0 Slot is 4, Port is 0
Type of VoicePort is FXS
Operation State is DORMANT
Administrative State is UP
No Interface Down Failure
Description is "Connection to PBX"
Noise Regeneration is enabled
Non Linear Processing is enabled
Music On Hold Threshold is Set to -50 dBm
In Gain is Set to 0 dB
Out Attenuation is Set to 0 dB
Echo Cancellation is enabled
Echo Cancel Coverage is set to 8 ms
Playout-delay Mode is set to default
Playout-delay Nominal is set to 60 ms
Playout-delay Maximum is set to 200 ms
Connection Mode is plar
Connection Number is 5265761
Initial Time Out is set to 10 s
Interdigit Time Out is set to 10 s
Ringing Time Out is set to 180 s
Companding Type is u-law
Region Tone is set for IN
Analog Info Follows:
Currently processing none
Maintenance Mode Set to None (not in mtc mode)
Number of signaling protocol errors are 0
Impedance is set to 600r Ohm
Wait Release Time Out is 30 s
Station name None, Station number None
Voice card specific Info Follows:
Signal Type is loopStart
Ring Frequency is 50 Hz
Hook Status is On Hook
Ring Active Status is inactive
Ring Ground Status is inactive
Tip Ground Status is inactive
Digit Duration Timing is set to 100 ms
InterDigit Duration Timing is set to 100 ms
Ring Cadence is defined by CPTone Selection
Ring Cadence are [4 2] [4 20] * 100 msec
Troubleshooting the Configuration
If you are having trouble placing a call and you suspect the problem is associated with the voice port configuration, you might be able to resolve the problem by performing one or more of the following tasks:
Ping the associated IP address to confirm connectivity, as follows:
Gateway# ping 172.20.59.93
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.20.59.93, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
If you cannot successfully ping your destination, refer to the Network Protocols Configuration Guide, Part 1.
Use the show voice port command to ensure that the port is enabled (administrative state is UP), as follows:
Gateway# sh voice port 4/0
Operation State is DORMANT
Administrative State is UP
If the port state is DOWN, as in the following display, use the no shutdown command to enable the port. (See the "Activating the Voice Port" section.)
Operation State is DOWN
Administrative State is DOWN
Fine-Tuning FXS Voice Ports
Depending on the specifics of your particular network, you might need to fine-tune the FXS voice port settings. Under most circumstances, the default values will suffice; however, if you need to change them, use the following commands in privileged EXEC mode.
Command
Purpose
configure terminal
Enters global configuration mode.
voice-portslot_number/port
Identifies the voice slot and port number you want to configure, and enters voice port configuration mode.
input gain value
Specifies (in decibels) the amount of gain to be inserted at the receiver side of the interface. Acceptable values are from -6 to 14.
output attenuation value
Specifies (in decibels) the amount of attenuation at the transmit side of the interface. Acceptable values are from 0 to 14.
echo-cancel enable
Enables echo-cancellation of voice that is sent out through the interface and received back on the same interface.
echo-cancel coverage value
Adjusts the size (in milliseconds) of the echo-cancel. Acceptable value is 8.
impedance value
Specifies the impedance of the port.
The functional values are 600r (the default) and complex2 (an 820 ohm in series with (220 ohm | 120 nF)).
non-linear
Enables nonlinear processing, which shuts off any signal if no near-end speech is detected. (Nonlinear processing is used with echo-cancellation.)
timeouts initialseconds
Specifies the number of seconds that the system will wait for the caller to enter the first digit of the digits to be dialed. Valid entries are from 0 to 120.
timeouts interdigit seconds
Specifies the number of seconds the system will wait (after the caller has entered the initial digit) for the caller to enter a subsequent digit. Valid entries are from 0 to 120.
timing digit milliseconds
If the voice port dial type is dual tone multifrequency (DTMF), configures the duration (in milliseconds) of the DTMF digit signal. The range of the duration is from 50 to 100; the default is 100.
timing inter-digit milliseconds
If the voice port dial type is DTMF, configures the duration (in milliseconds) of the DTMF interdigit signal. The range of the duration is from 50 to 500; the default is 100.
For complete information about configuration commands and about configuring LAN and WAN interfaces on your switch, refer to the Cisco IOS configuration guides and command references.
The following example shows how to use the fine-tune FXS commands:
Gateway# conf t
Enter configuration commands, one per line. End with CNTL/Z.
Gateway(config)# voice-port 4/0
Gateway(config-voiceport)# input gain 10
Gateway(config-voiceport)# output attenuation 10
Gateway(config-voiceport)# echo-cancel enable
Gateway(config-voiceport)# echo-cancel coverage 8
Gateway(config-voiceport)# non-linear
Gateway(config-voiceport)# timeouts initial 10
Gateway(config-voiceport)# timeouts interdigit 10
Gateway(config-voiceport)# timing digit 60
Gateway(config-voiceport)# timing inter-digit 60
To display the values configured, use the show running-config command, as follows:
Gateway# sh running-config
!
voice-port 4/0
input gain 10
output attenuation 10
echo-cancel coverage 8
timeouts initial 10
timeouts interdigits 10
timing digit 60
timing inter-digit 60
!
Activating the Voice Port
By default, configured voice ports are active. However, if you need to activate a port because it has been shut down explicitly, use the no shutdown command, as follows:
Gateway# conf t
Enter configuration commands, one per line. End with CNTL/Z.
Gateway(config)# voice-port 4/0
Gateway(config-voiceport)# no shutdown
Gateway(config-voiceport)#
00:55:53:%LINK-3-UPDOWN:Interface Foreign Exchange Station 4/0, changed state to up
To deactivate a port, use the shutdown command, as follows:
Gateway# conf t
Enter configuration commands, one per line. End with CNTL/Z.
Gateway(config)# voice-port 4/0
Gateway(config-voiceport)# shutdown
Gateway(config-voiceport)#
00:55:23:%LINK-3-UPDOWN:Interface Foreign Exchange Station 4/0, changed state to Administrative Shutdown
Sample Configuration
This section provides a sample configuration for sending a fax or a call from the Cisco 2610 (a voice-enabled router) to the eight-port FXS module on a Catalyst 4224, and vice versa.
Note You can substitute any voice-enabled router for the Cisco 2610 and any
Fast Ethernet interface connected to an IP network.
In the sample configuration illustrated in Figure 7-1, Fax1 is connected through an FXS port to the Cisco 2610 router. The router is connected through Fast Ethernet to the eight-port FXS module, which is connected through an FXS port to Fax2.
This section includes the following configuration-related samples:
