What are the requirements for Cisco Unified SRST?
For the most up-to-date information about Cisco Unified IP Phone support, the maximum number of Cisco Unified IP Phones, the maximum number of directory numbers (DNs) or virtual voice ports, and memory requirements for Cisco Unified SRST and Cisco Unified SIP SRST, see Cisco Unified SRST Supported Firmware, Platforms, Memory, and Voice Products .
How to create a SRST reference in Cisco communications manager?
If you have Cisco Communications Manager V3.3 or later versions, you must create an SRST reference and apply it to a device pool. An SRST reference is the IP address of the Cisco Unified SRST Router. From any page in Cisco Unified Communications Manager, click System and SRST .
What’s the default keepalive period for Cisco Unified SRST?
The default keepalive period is 30 seconds. If the phone has an active standby connection established with a Cisco Unified SRST router, the fallback process takes 10 to 20 seconds after connection with Cisco Unified CM is lost.
How long does it take Cisco Unified IP phone to fall back to SRST mode?
Note The time it takes for a Cisco Unified IP Phone to fallback to the SRST router can vary depending on the phone type. Phones such as the Cisco 7902, Cisco 7905, and Cisco 7912 can take approximately 2.5 minutes to fallback to SRST mode.
Which is CISCO ISR platform do I need to activate?
Multiple technology package licenses can be installed and activated on the Cisco 1900, 2900, 3900, 4300 and 4400 series ISR platforms. Individual features can be enabled or disabled by license keys. Feature licenses may be subscription-based, uncounted, or count-based licenses.
When does Cisco Unified SCCP and SIP SRST fail?
On H.323 gateways for SCCP SRST, when the WAN link fails, active calls from Cisco Unified IP phones to the PSTN are not maintained by default. Call preservation may work with the no h225 timeout keepalive command.
