CME as SRST

CUCM Configuration:

1. Go to the CM Administration page and select System > SRST
2. Click on Add New
3. Configure the Name as SiteCode_IPAddress (eg. NY_10.1.100.2)
4. Set the IP Address for both IP Address and SIP IP Address
5. Click Save
6. Go to System > Device Pool
7. Select the Remote Site Device Pool
8. Configure the corresponding SRST within the Device Pool
9. Click Save

VGW Configruation (CME-as-SRST):

1. license accept end user agreement (if running IOS Version 15.x or higher)
2. license modify priority cme-srst high (if running IOS Version 15.x or higher)
3. telephony-service
4. srst mode auto-provision none
5. srst dn template 1
6. srst dn line-mode octo
7. max-ephones 110
8. max-dn 300
9. ip source-address 10.1.89.2 port 2000
10. system message Life Alert Fallback
11. time-zone 5
12. max-conferences 4 gain -6
13. dn-webedit  
14. time-webedit  
15. transfer-system full-consult
16. transfer-pattern ....
17. transfer-pattern 9...........
18. transfer-pattern 9.......
19. secondary-dialtone 9

        Dial-peer configurations, conferencing or media resources, and MOH configuration would still be needed in this VGW configuration.




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SRST versus CME-in-SRST

Comparison chart of CME-in-SRST and SRST:

http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps2169/prod_qas0900aecd8028d113.html

The main questions to ask yourself whether to go for CME-as-SRST or SRST are:

1. How many phones do I need to support?
2. What features do I need during failover
3. Do I need to support a VG248 during failover?
4. Do I need to support hunt groups or call park?
5. Is conferencing required?
6. Are we utilizing secure voice? 

 



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Enhanced Survivable Remote Site Telephony (E-SRST)

Enhanced SRST (E-SRST) advantages over SRST:

• Automatic provisioning - it is integrated with CUCM and can be centrally configured/deployed from CUCM
• Automatic Synchronization - the Cisco Unified Messaging Gateway (required piece of hardware/software for E-SRST) synchronizes the configuration from the central site to the branch on a schedule. 
• Consistent Device Layout - phone displays, basic functions (extensions, soft-key templates, phone types, etc) are carried over in E-SRST.
• Full call control features during failover
•  Call forward no answer, call forward all, call forward busy
• Time of Day routing
• Class of Service restrictions for both incoming and outgoing
• Hunt Groups
• Call Park and Call Pickup

SRST advantages of Enhanced SRST (E-SRST):

• Lots cheaper
• No extra licenses required other than basic SRST licenses
• Unified Messaging Gateway not needed
• SIP SRST supported
• Who needs to pay the extra money to support call park/pickup, hunt groups, and TOD!?!

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Survivable Remote Site Telephony (SRST)

        How do you design Unified Communications failover for your remote sites or your primary site with a single CUCM Publisher or CUCM Business Edition? Survivable Remote Site Telephony (SRST) is the answer! SRST is a Cisco IOS Software capability that acts as a backup call-processing agent in the event of a link (typically WAN) failure, providing users with a subset of capabilities. However, the choice is not that easy as there are multiple versions and configuration scenarios:

• SRST
• H.323
• MGCP
• SIP
• CME as SRST
• Enhanced SRST
• Dual SRST

        In order to decide on which one to select you have to decide on the foundation first. How many users are at each SRST site and what phone models are utilized? The number of users and phone types will help you decide which SRST to select, which router to utilize, and what code and licensing you'll need to deploy. 

Requirements:

• The SRST routers need sufficient PSTN paths (FXO, PRI, BRI, etc.) to support the remote site users
• Decide on a list of requirements for SRST
• Inbound and outbound PSTN connectivity to all phones
• Voicemail
• Call Forward No Answer or Busy
• Extension expansion to full 10-digit DIDs of other sites
• Music on Hold locally streamed from SRST router
• Conferencing

CUCM Configuration:

1. Go to the CM Administration page and select System > SRST
2. Click on Add New
3. Configure the Name as SiteCode_IPAddress (eg. NY_10.1.100.2)
4. Set the IP Address for both IP Address and SIP IP Address
5. Click Save
6. Go to System > Device Pool
7. Select the Remote Site Device Pool
8. Configure the corresponding SRST within the Device Pool
9. Click Save

 

VGW Configurations:

1. license accept end user agreement (if running IOS Version 15.x or higher)
2. license modify priority cme-srst high (if running IOS Version 15.x or higher)
3. clock timezone [zone] [hours-offset]
4. call-manager-fallback
5. ip source-address [ip address] [port]
6. max-dn [max-directory-numbers] [dual-line | octo-line] [preference] [number]
7. huntstop channel [1-8]
8. max-ephone [max-phones]
9. date-format [mm-dd-yy | dd-mm-yy | yy-dd-mm | yy-mm-dd]
10. time-format [12 | 24]
11. system message [primary | secondary] [custom message]
12. secondary-dialtone [digit-string]

Example

1. clock timezone PST -8
2. call-manager-fallback
3. ip source-address 10.1.100.2  2000
4. max-dn 300 octo-line
5. huntstop channel 6
6. max-ephone 100
7. date-format mm-dd-yy
8. time-format 12
9. system message primary CM Fallback
10. secondary-dialtone 9

Verifying that SRST is enabled:

1. Show running-config
2. show call-manager-fallback all
3. show ephone (while in fallback)
4. debug ephone [keepalive | register | state | detail | error | statistics | pak | raw]

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