Focuses on configuring Foreign Exchange Station(FXS), Foreign Exchange Office(FXO) and T1 ports for transporting voice traffic.
1 FXS and FXO interfaces
An FXS itnerface is used to connect an analog device such as a fax machine, answering machine, or a modem to the network,An FXS interface supplies ring,voltage and dial tone for basic telephone equipment and PBXs.
FXO ports , on the other hand, are ananlog ports that connect office equipmnet such as a phone switch or PBX to the rotuer.
A small-business office that requires only a small number of outside lines would most likely use multiple analog FOX connections to make calls to the PSTN, If more lines are needed, a T1 would be used, Each FXO port on the router would connect to a single PSTN line , This line can carry only one call at a time.
T1 interfaces
A T1 connections allows connectivity of 24 individual channels that support 64Kbps each to the router, You can configure each channel can be configured to carry voice(or data) taffic. A T1 line is a digital connection, whereas the FXS and FXO connections are analog.
The direct-inward-dial command is used to enable Direct Inward Dialing(DID) on a dial peer. DID is a service of the local phone company that provides a block of numbers used to call into a company's own PBX. When DID is used, a company can assign a company employee a phone number without requiring a physical line into the PBX for each person. DID allows a caller to dial a phone extension directly.
Another command used within a dial peer is port x/x/x, where
(1) The first x is the slot
(2) The second x is the voice interface subunit
(3) The third x is the port number
Configuring FXS Connectivity
Phone(1,2)----switch----Router----FXS port ----Analog Phone
Task 1: Verify FXS Capability
Step 1: Power on the router and external switch if it is being used.
Step 2: Attach any cables necessary, and configure the router and switch/switch module appropriately until connectivity exists between the two Cisco IP Phones, Test the IP Phones by calling from one phone to another. Do not proceed until connectivity exists, Use the IP addressing scheme described in Table
The IP addressing please refenerce the uptables.
Step 3: Use the show hardware privileged mode command to verify that at least one FXS interface is installed in the router:
RouterVoIPX#show hardware
Step 4: Use the show voice port summary command to see a brief summary of the voice ports installed on a router, as demonstrated here:
RouterVoIPX#show voice port summary
Step 5: use the show voice port slot/subunit/port command to see detailed infoarmtion about the FXS card. For exampel ,If the FXS WIC is listed as 0/3/0 and 0/3/1 in the port column, the command would be show voice port 0/3/0 or show voice port 0/3/1
RouterVoIPX#show voice port 0/3/0
Step 6: Use the command show running-config| begin voice port command to see the section of the configuration that deals with the voice ports
Task 2: Connect and Configure the Analog Phone
Step 1: The FXS ports are labeled with a 0 or 1, Connect an analog phone to the router FXS port 0 using a phone cable.
Step 2: From global configuration mode on the router, configure a POTS dial peer for connectivily through the FXS port.Assign each dial peer a unique number, In this step ,dial peer 1 is used: RouterVoIPX(config)#dial-peer voice 1 pots
Step 3: The destionation-pattern number command defines the phone number to reach the analog phone that connects to the FXS port.such as Pod3 would use the phone number 5555088
Task 2: Configure the ISDN Switch Type
Step 1: From global configuration mode , use the command isdn switch-type primary-mi to set the PRI switch type This type must be the same one that the provider is using.
RouterVoIPX(config)#isdn switch-type primary-ni
_----------------------------------------------------------------------
Note: If the isdn switch-type command does not work on the router, you must likely need to enable the T1 controller by using the command card type t1x or card type t1x 1.
------------------------------------------------------------------------
Task 3: Configure the T1 Controller
Step 1: From privileged mode , look at the running configuration to determine the slot number for the T1 port or look back to your previous step nots:
RouterVoIPX#show running-config
Step 2: The network-clocl-participate command allows the ports on a specific module or voice WAN interface card(WWIC) to use the network clock for timing, The alternative is to restrict a device to use its own clocking signals.
From global configuration mode ,use the command network-clock-participate wic|slot X (where X is the physical slot where the T1 port is unstalled) Whether you use the wic parameter or the slot parameter is based on what was documented with the show diag command .
RouterVoIPX(config)#network-clock-participate wic x or
RouterVoIPX(config)#network-clock-participate slot X
Step 3: From global configuration mode , enter the mode to control the T1 port by using the controller t1 slot/port_or_sunslot/port command. The slot/port_or_subslot/port parameters are the same as what was researched earlier , An example in the 2811 router would be controller t1 1/0/0 or controller t1 1/0 , depending on the NM-HDV2-1T1 type.
RouterVoIPX(config)#controller t1 slot/port_or_subslot/port
Step 4: In T1 controller mode , enter the command framing esf to set the type of framing used.
RouterVoIPX(config-controller)#framing esf
Step 5: In T1 controller mode , enter the command linecode b8zs to set the line coding .
RouterVoIPX(config-controller)#linecode b8zs
Step 6: Set the clocking to the line with the clock source line command
RouterVoIPX(config-controller)#clock source line
................................................................................
Note: If an error appears that this command is unavilable ,this is because the T1 controller is automatically clocking from internal line.
.................................................................................
Step 7: From the T1 controller configuration mode ,use the command pri-group timeslots 1-12 to assign the first 12 channels to the PRI:
RouterVoIPX(config-controller)#pri-group timeslots 1-12
...................................................................................Note: If an error appears that there are not enough DSP resources, reduce the number of timeslots to eight(1-8 in the command) or a lower number. depending on your DSP resources. The B channels on the T1 controller should go up ,and you should see messages to that effect.
...................................................................................Step 8: Use the command show isdn status, and verify that Layer 1 is ACTIVE and that Layer 2 show MULTIPLE_FRAME_ESTABLISHED
RouterVoIPX#show isdn status
...................................................................................
Note: If the command output does not show ACTIVE and MULTIPLE_FRAME_ESTABLISHED, perform appropriate troubleshooting.
...................................................................................
Step 9: In the show isdn status command output, make a note of what serial port is listed on the second line of the output, This information is needed in the next step, An example of the serial output listing is ISDN Serial1/0/0:23 or serial1/0:23
Step 10: Use the show interface serial mod/port_or_subslot/port:23 command to verify that the interface status is up and up. Examples of this command on a 2811 router are show interface serial 1/0/0:23 and show interface serial 1/0:23
Task 4: Configure the Dial Peers
Step 1: Before configuring the dial peers, test standard phone configuration by calling one of the IP Phones from the analog phone attached to the router FXS port, Only four digits are need to dial from the FXS analog phone to the Cisco IP Phone.
Also , From the Cisco IP Phone, dial the seven-digit number for the analog phone connected to the FXS router port, Do not proceed unless these connections work.
