Cisco Unified Survivable Remote Site Telephony: Difference between revisions

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'''SRST ''(Cisco Unified Survivable Remote Site Telephony)''''' is a service on voice-capable Cisco ISR (Integrated services) routers that provides a local fallback for Cisco IP phones that are connected to CUCM (particularly over WAN) when the cluster is unreachable such as from an internet outage or VPN issue. It's most common in branch offices and remote sites, as CUCM clustering is not always possible, and ~~is not designed for this purpose~~. There are two modes that SRST can be used in.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/srst_overview.html#Cisco_Reference.dita_4b62f3d9-b102-4a13-9ee5-d9a51b4ebad7:~:text=Unified%20SRST%20mode.-,Enhanced%20SRST%20Mode,-Enhanced%20SRST%20mode</ref> Unified SRST Mode, used by default, can handle basic call signaling and trunks for voice calls. Enhanced SRST Mode enables video support, BLFs, Basic Automatic Call Distribution (B-ACD), Hunt Groups, cBarge, Privacy, and shared lines. SRST is licensed per endpoint with Enhanced SRST ~~typically~~ being more expensive. SRST is configured a lot like other ISR voice services such as Cisco Unified Communications Manager Express (CME), using '''call-manager-fallback'''. Historically, Cisco Unified SRST Manager was a provisioning server to automate ~~configuation~~ from the CUCM cluster to SRST and E-SRST servers. It was deprecated ~~startiing~~ with release 12.2.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/enhanced_srst.html#:~:text=Unified%20Communications%20Manager-,Migration%20from%20Cisco%20Unified%20SRST%20Manager%20to%20Unified%20E%2DSRST,Configure%20Unified%20E%2DSRST%20and%20SCCP%3A%20Configure%20Unified%20E%2DSRST.,-For%20information%20on</ref>

'''SRST ''(Cisco Unified Survivable Remote Site Telephony)''''' is a service on voice-capable Cisco ISR (Integrated services) routers that provides a local fallback for Cisco IP phones that are connected to CUCM (particularly over WAN) when the cluster is unreachable such as from an internet outage or VPN issue. It's most common in branch offices and remote sites without a subscriber node, as CUCM clustering is not always possible due to latency recommendations, network speeds and the 8 (10 in CUCM 15+) call processing server limit in a CUCM cluster.

There are two modes that SRST can be used in.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/srst_overview.html#Cisco_Reference.dita_4b62f3d9-b102-4a13-9ee5-d9a51b4ebad7:~:text=Unified%20SRST%20mode.-,Enhanced%20SRST%20Mode,-Enhanced%20SRST%20mode</ref> Unified SRST Mode, used by default, can handle basic call signaling and trunks for voice calls. Enhanced SRST Mode enables video support, BLFs, Basic Automatic Call Distribution (B-ACD), Hunt Groups, cBarge, Privacy, and shared lines. SRST is licensed per endpoint with Enhanced SRST being more expensive. SRST is configured a lot like other ISR voice services such as Cisco Unified Communications Manager Express (CME), using '''call-manager-fallback'''. Historically, Cisco Unified SRST Manager was a provisioning server to automate configuration from the CUCM cluster to SRST and E-SRST servers. It was deprecated starting with release 12.2.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/enhanced_srst.html#:~:text=Unified%20Communications%20Manager-,Migration%20from%20Cisco%20Unified%20SRST%20Manager%20to%20Unified%20E%2DSRST,Configure%20Unified%20E%2DSRST%20and%20SCCP%3A%20Configure%20Unified%20E%2DSRST.,-For%20information%20on</ref>

SRST does not in any way, shape, or form communicate with the CUCM cluster. The only configuration in CUCM relating to SRST are SRST References. Which when added to a Device Pool, tell the phones what the IP address of the SRST server is. The phone then uses the SRST as a standby server.

== Configuration in CUCM ==

A system administrator can view, edit, and add SRST references in Cisco Unified CM Administration > System > SRST. By default, there is a "Disabled" reference, used in the default device pool out of the box, which does not specify an SRST server. And a "Use Default Gateway" reference. Used where the router on the network is running SRST. When adding a new reference, an IPv4 and IPv6 address can be added. If the SRST server is using alternate ports, a SIP port can be set in "SIP Port", and a SCCP port can be set in "Port". The SRST Certificate Provider port cannot be changed. The SRST reference is set in the Device Pool. When configuring a Device Pool, a SRST reference can be set in Roaming Sensitive Settings. All phones in the Device Pool can use that SRST server.

[[Category:Cisco Systems]]

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-'''SRST ''(Cisco Unified Survivable Remote Site Telephony)''''' is a service on voice-capable Cisco ISR (Integrated services) routers that provides a local fallback for Cisco IP phones that are connected to CUCM (particularly over WAN) when the cluster is unreachable such as from an internet outage or VPN issue. It's most common in branch offices and remote sites, as CUCM clustering is not always possible, and is not designed for this purpose. There are two modes that SRST can be used in.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/srst_overview.html#Cisco_Reference.dita_4b62f3d9-b102-4a13-9ee5-d9a51b4ebad7:~:text=Unified%20SRST%20mode.-,Enhanced%20SRST%20Mode,-Enhanced%20SRST%20mode</ref> Unified SRST Mode, used by default, can handle basic call signaling and trunks for voice calls. Enhanced SRST Mode enables video support, BLFs, Basic Automatic Call Distribution (B-ACD), Hunt Groups, cBarge, Privacy, and shared lines. SRST is licensed per endpoint with Enhanced SRST typically being more expensive. SRST is configured a lot like other ISR voice services such as Cisco Unified Communications Manager Express (CME), using '''call-manager-fallback'''. Historically, Cisco Unified SRST Manager was a provisioning server to automate configuation from the CUCM cluster to SRST and E-SRST servers. It was deprecated startiing with release 12.2.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/enhanced_srst.html#:~:text=Unified%20Communications%20Manager-,Migration%20from%20Cisco%20Unified%20SRST%20Manager%20to%20Unified%20E%2DSRST,Configure%20Unified%20E%2DSRST%20and%20SCCP%3A%20Configure%20Unified%20E%2DSRST.,-For%20information%20on</ref>
+'''SRST ''(Cisco Unified Survivable Remote Site Telephony)''''' is a service on voice-capable Cisco ISR (Integrated services) routers that provides a local fallback for Cisco IP phones that are connected to CUCM (particularly over WAN) when the cluster is unreachable such as from an internet outage or VPN issue. It's most common in branch offices and remote sites without a subscriber node, as CUCM clustering is not always possible due to latency recommendations, network speeds and the 8 (10 in CUCM 15+) call processing server limit in a CUCM cluster.
+There are two modes that SRST can be used in.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/srst_overview.html#Cisco_Reference.dita_4b62f3d9-b102-4a13-9ee5-d9a51b4ebad7:~:text=Unified%20SRST%20mode.-,Enhanced%20SRST%20Mode,-Enhanced%20SRST%20mode</ref> Unified SRST Mode, used by default, can handle basic call signaling and trunks for voice calls. Enhanced SRST Mode enables video support, BLFs, Basic Automatic Call Distribution (B-ACD), Hunt Groups, cBarge, Privacy, and shared lines. SRST is licensed per endpoint with Enhanced SRST being more expensive. SRST is configured a lot like other ISR voice services such as Cisco Unified Communications Manager Express (CME), using '''call-manager-fallback'''. Historically, Cisco Unified SRST Manager was a provisioning server to automate configuration from the CUCM cluster to SRST and E-SRST servers. It was deprecated starting with release 12.2.<ref>https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cusrst/admin/sccp_sip_srst/configuration/guide/SCCP_and_SIP_SRST_Admin_Guide/enhanced_srst.html#:~:text=Unified%20Communications%20Manager-,Migration%20from%20Cisco%20Unified%20SRST%20Manager%20to%20Unified%20E%2DSRST,Configure%20Unified%20E%2DSRST%20and%20SCCP%3A%20Configure%20Unified%20E%2DSRST.,-For%20information%20on</ref>
+SRST does not in any way, shape, or form communicate with the CUCM cluster. The only configuration in CUCM relating to SRST are SRST References. Which when added to a Device Pool, tell the phones what the IP address of the SRST server is. The phone then uses the SRST as a standby server.
+== Configuration in CUCM ==
+A system administrator can view, edit, and add SRST references in Cisco Unified CM Administration > System > SRST. By default, there is a "Disabled" reference, used in the default device pool out of the box, which does not specify an SRST server. And a "Use Default Gateway" reference. Used where the router on the network is running SRST. When adding a new reference, an IPv4 and IPv6 address can be added. If the SRST server is using alternate ports, a SIP port can be set in "SIP Port", and a SCCP port can be set in "Port". The SRST Certificate Provider port cannot be changed. The SRST reference is set in the Device Pool. When configuring a Device Pool, a SRST reference can be set in Roaming Sensitive Settings. All phones in the Device Pool can use that SRST server.
+<references />
+[[Category:Cisco Systems]]