====== SRST ======

===== General =====

  * 720 Cisco IP Phones when using a ISR 3845

==== IOS SRST ====
  * call preservation
  * auto-provisioning
  * failover
  * SRTP encryption

==== CME SRST ====
  * All IOS SRST features except SRTP
  * Paging
  * Conferencing
  * Hunt groups
  * B-ACD
  * Call park, call pickup, call pickup groups
  * Overlay DN, softkey templates
  * Cisco IP Communicator 2.0
  * Cisco Unified Video Advantage 2.0
  * Integrate with Cisco Unity with MWI at remote sites
  * Does not support SIP or MGCP phones, use SIP SRST or MGCP Gateway Fallback instead.

===== Class of Service =====
  * Configure COS following the instructions in [[gw-cos|Gateway COS]]
  * Using the cor incoming command within the call-manager-fallback configuration mode, configure the complex corlists acting as "calling search spaces" to be incoming corlists assigned to the various phone DNs:
<code>
call-manager-fallback
  cor incoming InternalCSS default
  cor incoming LocalCSS 1 3001 - 3003
  cor incoming LDCSS 2 3004
  cor incoming IntlCSS 3 3010
</code>
<note>• In SRST version 2.0, available on Cisco IOS Release 12.2(8)T or later, the maximum number of cor incoming statements allowed under call-manager-fallback is 5 (plus the default statement).

• In SRST version 3.0, available on Cisco IOS Release 12.3(4)T or later, the maximum number of cor incoming statements allowed under call-manager-fallback is 20 (plus the default statement).
</note>