This document will discuss into the differences of using Enhanced SRST vs the traditional SRST with both remote site survivability in the event of WAN outage. Apart from improved end user experience, E-SRST is end-user also provides more customized solution.
SRST is an IOS router feature at the branch. E-SRST however runs on a SRE module at the central site.
E-SRST functionality provides automated remote site provisioning of the following advanced telephony features in survivable mode by gathering the information from CUCM:
- End-user phones and extensions (speed dials, lines, softkeys)
- Voicemail and call forward configuration
- Call routing restrictions (local and long distance, and time of day)
- Call pickup and group pickup
- Hunt groups
In a nut shell, E-SRST builds on top of SRST by automatically synchronizing user, phone, hunt group, partitions etc from CUCM to CME. Any change on CUCM is propagated to the branch sites without admin intervention, so when the WAN is down, the phone resembles the last changes done on CUCM.
Below is the table showing major differences between SRST and E-SRST –