Configuring Access Gateways

To make the Cisco CallManager aware of the gateways it can use, you must add them to the configuration. You must add the gateways to the CallManager database based on the protocol the CallManager uses to communicate with the gateway. After you have added the gateway to the CallManager configuration, you can include it in your route plan design to allow your IP Phones to dial off the local network. The full route plan design and configuration is covered in Chapters 10-13.

Note

This section focuses on configuring the CallManager to communicate with the gateway. You must have also configured the gateway to communicate with the CallManager and additional networks such as a PBX or the PSTN. Although this book presents brief configuration examples, the full gateway configuration is covered in depth in Authorized Self-Study Guide: Cisco Voice over IP (CVOICE), Second Edition and Cisco Voice Gateways and Gatekeepers.

 

H.323 Gateway Configuration

Complete these steps to add an H.323 gateway to your CallManager configuration:

Step 1.	Choose Gateway from the Device menu in the Cisco CallManager Administration window.
Step 2.	Click the Add a New Gateway link and choose H.323 Gateway from the Gateway Type menu.
Step 3.	Cisco CallManager automatically populates the Device Protocol field with H.225. Click Next.
Step 4.	In the Device Name field shown in Figure 9-1, enter the IP address (recommended to remote DNS reliance) or hostname of the Cisco router that will be acting as the gateway.   Figure 9-1. CallManager H.323 Gateway Configuration
Step 5.	Assign the gateway to a device pool.
Step 6.	Click Insert when finished.

Tip

The prior configuration allows you to add an H.323 gateway to the CallManager configuration. However, many more configuration options are available. For information on all the settings available in the Gateway Configuration window, refer to the Cisco CallManager "Help for this Page" option (available from the CCMAdmin Help menu). This page provides a brief explanation for each configuration field available.

Because H.323 is a peer-to-peer protocol, you must configure most of the gateway configuration using Cisco IOS software on the gateway itself. Table 9-1 lists the Cisco IOS commands you can use to configure an H.323 voice gateway.

Table 9-1. Cisco IOS Commands to Configure an H.323 Voice Gateway

Command	Description
H323_GW(config)# gateway	Enables H.323 VoIP gateway functionality. After you enable the gateway, it attempts to discover a gatekeeper by using an H.323 gatekeeper request message.
H323_GW(config)# voice class h323 tag	Creates an H.323 voice class that is used to configure a TCP timeout duration.
H323_GW(config-class)# h225 tcp timeout seconds	Configures the H.225 TCP timeout duration in seconds. Possible values are 0 to 30. The default is 15. If you specify 0, the H.225 TCP timer is disabled. When the duration (seconds) of the H.225 TCP is exceeded, the voice gateway will use the next ordered dial peer (controlled via the preference command), which points to a backup Cisco CallManager.
H323_GW(config)# dial-peer voice tag voip	Creates a VoIP dial peer.
H323_GW(config-dial-peer)# voice class h323 tag	Assigns the previous created voice class to this dial peer.
H323_GW(config-dial-peer)# destination-pattern dial-string	Configures the dial string that this dial peer matches.
H323_GW(config-dial-peer)# session target ipv4:ccm-ip-address	Identifies the IP address to route a call to when the destination pattern in the previous command is matched. The IP address is the address of the Cisco CallManager on an H.323 gateway.
H323_GW(config-dial-peer)# preference 010	Assigns a preference to a dial peer when multiple dial peers contain the same destination pattern but different session targets. 0 is the highest, 10 is the lowest (used to configure Cisco CallManager redundancy on H.323 gateways).
H323_GW(config-dial-peer)# dtmf-relay h245-alphanumeric	Configures the gateway to use out-of-band DTMF relay. DTMF relay sends DTMF tones across the signaling channel, instead of as part of the voice stream. DTMF relay is needed when you are using a low-bit-rate coder-decoder (codec) for voice compression, because the potential exists for DTMF signal loss or distortion.

Example 9-1 shows an H.323 gateway that has been configured for Cisco CallManager redundancy.

Example 9-1. H.323 Gateway Configuration

H323_GW(config)#!Creates VoIP dial-peer 101
H323_GW(config)#dial-peer voice 101 voip
H323_GW(config-dial-peer)#!Sends DTMF digits out-of-band
H323_GW(config-dial-peer)#dtmf-relay h245-alphanumeric
H323_GW(config-dial-peer)#!Matches all 4-digit extensions
H323_GW(config-dial-peer)#destination-pattern ....
H323_GW(config-dial-peer)#!Target address of Primary CallManager
H323_GW(config-dial-peer)#session target ipv4:10.1.1.101
H323_GW(config-dial-peer)#!Selects this as the preferred dial-peer
H323_GW(config-dial-peer)#preference 0
H323_GW(config)#!Creates VoIP dial-peer 102
H323_GW(config)#dial-peer voice 102 voip
H323_GW(config-dial-peer)#dtmf-relay h245-alphanumeric
H323_GW(config-dial-peer)#destination-pattern ....
H323_GW(config-dial-peer)#!Target address of Secondary CallManager
H323_GW(config-dial-peer)#session target ipv4:10.1.1.102
H323_GW(config-dial-peer)#!Selects this as the secondary dial-peer
H323_GW(config-dial-peer)#preference 1

Call Classification

The Call Classification feature, introduced in Cisco CallManager Release 4.1, provides the ability to configure gateways and trunks as on the network (OnNet) or off the network (OffNet) at the device or at the global level. As a result, a call through these devices is classified as either OnNet or OffNet. With these classifications, Cisco CallManager provides the ability to restrict OnNet-to-OffNet transfers and to drop an ad hoc conference when no OnNet parties remain in the conference. This field provides an OnNet or OffNet alerting tone when the call is classified as OnNet or OffNet, respectively.

The corresponding Call Classification field in the gateway and trunk configuration windows, shown in Figure 9-2, marks the corresponding devices as OnNet or OffNet or Use System Default. The default Call Classification settings are OnNet for all IP Phones and intercluster trunks and Use System Default (which is OffNet) for other gateways.

Figure 9-2. CallManager Call Classification Gateway Configuration

In Cisco CallManager 4.X releases, Cisco defined a new, global service parameter called Call Classification. The default value of this parameter is OffNet. When Use System Default is selected at the device level for a particular gateway or trunk, the value of the service parameter (defined using the Service > Service Parameters > Cisco CallManager menu option in CCMAdmin) is used to judge the device as OnNet or OffNet. Therefore, gateways are classified as external (OffNet) by default.

FXS ports and IP Phones are not configurable and are always treated as OnNet.

The parameters that determine whether a transfer is allowed or restricted are as follows:

• The Call Classification setting on the gateway or trunk.
• The Call Classification setting and Allow Device Override check box setting on the route pattern. If the Allow Device Override check box is checked, the Call Classification setting on the gateway or trunk takes precedence.
• The Service parameter Block OffNet to OffNet Transfer. When this parameter is set to False, the transfer is not restricted. When this parameter is set to True (the default) and the transfer is initiated between two OffNet parties, the transfer is blocked.

Note

The ability to restrict external transfers and to drop an ad hoc conference when no OnNet parties remain on the call help to prevent toll fraud. Preventing toll fraud and many other IP telephony security considerations are covered in detail in Chapter 22, "Preventing Toll Fraud."

 

MGCP Gateway Configuration

Complete these steps to add an MGCP gateway to the CallManager configuration:

Step 1.	Choose Gateway from the Device menu in the Cisco CallManager Administration window.
Step 2.	Click the Add a New Gateway link and choose one of the various MGCP-capable devices from the Gateway Type menu.

Note

Selecting a Cisco router by the actual model of router from the Gateway Type drop-down menu automatically chooses the MGCP protocol for communication.

Step 3.	Cisco CallManager automatically populates the Device Protocol field with the MGCP protocol. Click Next.
Step 4.	For the Domain Name field, shown in Figure 9-3, enter the unique hostname (or fully qualified domain name [FQDN]) of the Cisco device that will be acting as the gateway.   Figure 9-3. CallManager MGCP Gateway Configuration
Step 5.	Assign the gateway to a Cisco CallManager group for redundancy.
Step 6.	Choose the type of network modules that are used in the MGCP gateway.
Step 7.	Choose the type of voice interface cards (VICs) that are used in the subunit slots of the MGCP gateway.
Step 8.	Click Insert.
Step 9.	Click an endpoint identifier (for example, 1/0/0) to configure device protocol information and add ports for the installed types of VICs.

Table 9-2 lists the IOS commands to help configure endpoint identifiers for analog devices connected to the MGCP gateway.

Table 9-2. Cisco IOS Commands to Configure an MGCP Voice Gateway

Command	Description
Router(config)# hostname MGCP_GW	Assigns a unique name to the voice gateway so that the Cisco CallManager server can identify it. This name must be unique throughout the network.
MGCP_GW(config)# mgcp	Enables MGCP on the voice gateway.
MGCP_GW(config)# mgcp call-agent ip-address	Identifies the primary Cisco CallManager for the gateway.
MGCP_GW(config)# ccm-manager mgcp	Indicates to the gateway that the Cisco CallManager is using MGCP.
MGCP_GW(config)# ccm-manager redundant-host ip-address1 ip-address2	Specifies the secondary and tertiary Cisco CallManager servers that are used for Cisco CallManager redundancy.
MGCP_GW(config)# ccm-manager switchback {graceful | immediate | schedule-time hh:mm | uptime-delay minutes }	Specifies how the gateway behaves if the primary server becomes unavailable and later becomes available again. The keywords and arguments are as follows: graceful Completes all outstanding calls before returning the gateway to the control of the primary Cisco CallManager server. immediate Returns the gateway to the control of the primary Cisco CallManager server without delay, as soon as the network connection to the server is reestablished. schedule-time hh:mm Returns the gateway to the control of the primary Cisco CallManager server at the specified time, where hh:mm is the time according to a 24-hour clock. If the gateway reestablishes a network connection to the primary server after the configured time, the switchback occurs at the specified time on the following day. uptime-delay minutes Returns the gateway to the control of the primary Cisco CallManager server when the primary server runs for a specified number of minutes after a network connection is reestablished to the primary server. Valid values are from 1 to 1440 (from 1 minute to 24 hours).
MGCP_GW(config)# mgcp dtmf-relay voip codec all mode out-of-band	Configures the gateway to use out-of-band DTMF relay for all codecs. If this command is not configured, DTMF tones will not be regenerated correctly on remote endpoints.
MGCP_GW(config)# dial-peer voice tag pots	Creates a POTS dial peer.
MGCP_GW(config-dial-peer)# application MGCPAPP	Configures the dial peer to use the MGCP application. The MGCPAPP option is case sensitive in some Cisco IOS software releases. Unless you know that your version is not case sensitive, always issue this command in uppercase. You can check whether your version is case sensitive after you configure this command by looking at the output of the show running-config command.
MGCP_GW(config-if)# isdn bind-l3 ccm-manager	Places a PRI or BRI ISDN interface under CallManager control (known as backhauling the interface). This allows CallManager to control all L3 (network layer) communication of the PRI/BRI line. This command is entered under the interface configuration mode for the PRI/BRI connection.

Example 9-2 shows an MGCP gateway that has been configured for Cisco CallManager redundancy placing one FXS port under CallManager control.

Example 9-2. MGCP Gateway Configuration Example

Router(config)#!The hostname links the gateway in the CallManager configuration
Router(config)#hostname MGCP_GW
Router(config)#!enables the protocol
MGCP_GW(config)#mgcp
Router(config)#!Identifies the IP address of the primary CallManager
MGCP_GW(config)#mgcp call-agent 10.1.1.1
Router(config)#!Uses MGCP to communicate with the CallManager
MGCP_GW(config)#ccm-manager mgcp
Router(config)#!Identifies secondary CallManager
MGCP_GW(config)#ccm-manager redundant-host 10.1.1.2
Router(config)#!All DTMF digits sent out-of-band
MGCP_GW(config)#mgcp dtmf-relay voip codec all mode out-of-band
Router(config)#!Creates POTS dial-peer 101
MGCP_GW(config)#dial-peer voice 101 pots
Router(config-dial-peer)#!Selects the physical port the CallManager will control
MGCP_GW(config-dial-peer)#port 1/0/0
MGCP_GW(config-dial-peer)#!Places the port under CallManager control
MGCP_GW(config-dial-peer)#application MGCPAPP

Non-IOS MGCP Gateway Configuration

You can equip Cisco Catalyst 6500 series switches with a variety of modules, allowing them to act as a voice gateway. If the Catalyst 6500 is running the NativeIOS software image, you can perform the configuration as you would a typical Cisco gateway. However, the Cisco Catalyst 6500 can also function using the CatalystOS operating system. If you are operating in this type of environment, you will need to configure the CallManager to communicate with the 6500 as a Non-IOS MGCP Gateway. Complete the following steps to add a non-IOS MGCP gateway to Cisco CallManager:

Step 1.	Choose Gateway from the Device menu in the Cisco CallManager Administration window.
Step 2.	Click the Add a New Gateway link and choose one of the various non-IOS MGCP devices from the Gateway Type menu. If you have selected the Cisco Catalyst 6000 T1 or E1 VoIP Gateway module (WS-X6608), the Device Protocol field provides you with the option of specifying either digital access PRI or digital access T1. After you have made your selection, click Next.
Step 3.	Add the MAC address to the MAC Address field. Cisco CallManager associates with a non-IOS MGCP gateway (such as the Cisco Catalyst 6608 T1 or E1 blade) through the MAC address of the port. The show port module command from enable mode on the Cisco Catalyst 6000 is a quick way to identify and list the MAC addresses of each digital gateway port on the Voice T1/E1 and Services (WS-X6608) module:   Cat6000(enable)show port 3 Port DHCP MAC-Address IP-Address Subnet-Mask -------- ------- ----------------- --------------- --------------- 3/1 disable 00-30-b6-3e-8e-c4 172.16.10.121 255.255.255.0 3/2 disable 00-30-b6-3e-8e-c5 172.16.20.122 255.255.255.0 3/3 disable 00-30-b6-3e-8e-c6 172.16.30.123 255.255.255.0 3/4 disable 00-30-b6-3e-8e-c7 172.16.40.124 255.255.255.0 3/5 disable 00-30-b6-3e-8e-c8 172.16.1.125 255.255.255.0 3/6 disable 00-30-b6-3e-8e-c9 172.16.1.126 255.255.255.0 3/7 disable 00-30-b6-3e-8e-ca 172.16.1.127 255.255.255.0 3/8 disable 00-30-b6-3e-8e-cb 172.16.1.128 255.255.255.0 To display detailed information about a specific port on the module, use the show port mod/port command.
Step 4.	Assign the gateway to a device pool.
Step 5.	Configure additional parameters as desired, and click the Insert button when finished.
Step 6.	Repeat Steps 1 through 5 for each T1 or E1 port that you want to add as a gateway in Cisco CallManager administration.

After you add the gateway to the database, Cisco CallManager creates a configuration file in the cluster on the Cisco TFTP server, and this file is where the T1 or E1 port downloads its configuration details, which include an ordered list of Cisco CallManager servers.

On the gateway itself (Cisco Catalyst 6500 T1 or E1 port), it is recommended that you statically configure the IP address, subnet mask, default gateway, and TFTP server address of each T1 and E1 port that is used as a digital gateway. The TFTP server address should be the IP address of the Cisco CallManager to which you want the port to register and download its configuration file. The following command statically configures the following voice port settings: IP address, subnet mask, VLAN ID, TFTP server IP address, and default gateway:

 Cat6000 (enable) set port voice in 3/1 dhcp disable 172.16.1.121 255.255.255.0
 vlan 1 tftp 172.16.1.5 gateway 172.16.1.1

Note

When a port resets, the module has the ability to reset the adjoining port because all eight ports on the WS-X6608 module share the same XA processor. This reset process creates a domino effect, and all of the ports on the module reset, creating the following error message:

%SYS-4-MODHPRESET:Host process (860) mod_num/port_num got reset asynchronously

If you are not going to use a port, you should either disable the port or configure and register it to Cisco so that it does not continually perform an asynchronous reset.

When you have successfully placed an individual 6608 T1 port under CallManager MGCP control, you will see the following output:

AV-6509-1 (enable) show port 2/1

Port Name Status Vlan Duplex Speed Type
----- ------------------ ---------- ---------- ------ ----- ------------
 2/1 notconnect 1 full 1.544 T1

Port DHCP MAC-Address IP-Address Subnet-Mask
-------- ------- ----------------- --------------- ---------------
 2/1 disable 00-30-b6-3e-8e-c4 172.16.1.121 255.255.255.0

Port Call-Manager(s) DHCP-Server TFTP-Server Gateway
-------- ----------------- --------------- --------------- --------------
 2/1 172.16.1.5 - 172.16.1.5 172.16.1.1

Port DNS-Server(s) Domain
-------- ----------------- ----------------------------------------------
 2/1 - -

Port CallManagerState DSP-Type
-------- ---------------- --------
 2/1 registered C549