In Cisco Unified Communications Manager Administration, use the System > SRST menu path to configure SRST references.
A survivable remote site telephony (SRST) reference comprises the gateway that can provide limited Cisco Unified Communications Manager functionality when all other Cisco Unified Communications Manager servers for a device are unreachable. Typically assigned to device pools, SRST references determine the gateways where calling devices search when they attempt to complete a call if Cisco Unified Communications Manager is unavailable. For more detailed information on SRST references, see topics related to SRST reference configuration settings in the Cisco Unified Communications Manager System Guide.
SRST reference deletion
You cannot delete SRST references that device pools or other items are using. To find out which device pools are using the SRST reference, click the Dependency Records link from the SRST Reference Configuration window. If the dependency records are not enabled for the system, the dependency records summary window displays a message. If you try to delete an SRST reference that is in use, Cisco Unified Communications Manager displays an error message. Before deleting an SRST reference that is currently in use, you must perform either or both of the following tasks:
Assign a different SRST reference to any device pools that are using the SRST reference that you want to delete.
Delete the device pools that are using the SRST reference that you want to delete.
Before initiating a deletion, check carefully to ensure that you are deleting the correct SRST reference. You cannot retrieve deleted SRST references. If an SRST reference is accidentally deleted, you must rebuild it.
The following table describes the SRST reference settings.
Table 1 SRST reference settings
Enter a name in the SRST Reference Name field. The name can comprise up to 50 alphanumeric characters and can contain any combination of spaces, periods (.), hyphens (-), and underscore characters (_). Ensure that each SRST reference name is unique.
Use concise and descriptive names for your SRST references.
Enter the port number for this SRST reference. Default value specifies 2000.
Change this value only if it does not match the gateway port setting. This value and the gateway port setting must match.
Enter the IP address of the gateway for devices in a device pool to use as an SRST reference.
SIP Network/IP Address
Enter the IP address of the server that the phones that are running SIP will use when in SRST mode.
You must configure the SIP Network/IP Address field and the SIP Port field for a SIP device to fall back to the SRST-enabled gateway
Enter the SIP port of the SRST gateway. Default value specifies 5060.
Is SRST Secure?
After you verify that the SRST-enabled gateway contains a self-signed certificate, check this check box.
After you configure the SRST and reset the gateway and dependent phones, the Cisco CTL Provider service authenticates to the Certificate Provider service on the SRST-enabled gateway. The Cisco CTL client retrieves the certificate from the SRST-enabled gateway and stores the certificate in the Cisco Unified Communications Manager database.
To remove the SRST certificate from the database and phone, uncheck this check box, click Save, and reset the dependent phones.
SRST Certificate Provider Port
This port monitors requests for the Certificate Provider service on the SRST-enabled gateway. Cisco Unified Communications Manager uses this port to retrieve the certificate from the SRST-enabled gateway. The Cisco SRST Certificate Provider default port equals 2445.
After you configure this port on the SRST-enabled gateway, enter the port number in this field.
You may need to configure a different port number if the port is currently used or if you use a firewall and you cannot use the port within the firewall.
This button displays only after you check the Is SRST Secure? check box and click Save.
After you click this button, the Cisco CTL client replaces the existing SRST-enabled gateway certificate that is stored in the Cisco Unified Communications Manager database, if a certificate exists in the database. After you reset the dependent phones, the TFTP server sends the cnf.xml file (with the new SRST-enabled gateway certificate) to the phones.