Need Help for Configuring SRST on 2801 Router ASAP

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Apr 20th, 2010
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Hii all,


I have a Cisco 2801 Router.I need to configure SRST on that Router

So can u pls help me with da complete SRST configs on the router ASAP

I would kindly request to provide a detailed Configuration with an example if possible

A Sincere help will be highly appreciated.

Thanking You in advance for ur kind cooperation

Awaiting ur prompt response.


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sanjeevreddyallala Tue, 04/20/2010 - 03:50
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Hi Kajha,

I assume you have seperate device pool for your phones on remote site.

1. create a new SRST reference or use default GW (I guess in ur case you dont need to create one)

2. Under device pool settings>roaming sensitive settings>SRST refernce>select the one appropriate configure your remote GW as bellow based on your directory requirements


ip source-address port 2000

max-ephones 50
max-dn 100

Now test the connection as bellow

4. Turn of CUCM service under serviceblity

5. now IP phones on remote site should fall back to SRST local GW

6. you can see SRST IP address on your IPPhone device configuration settings (I guess u need to reset the IP Phones)

Note: Regardless of your remote GW is MGCP or H323 the above is SRST config (I guess so)



sanjeevreddyallala Tue, 04/20/2010 - 03:52
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Sorry I mean you dont need to reset your ip phones as SRST means automatic fallback...

Arifuddinkhaja Tue, 04/20/2010 - 04:34
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Dear Sanjeev

Thankx 4 ur prompt response.I wud to like know exactly how to config 2801 for Cisco IOS SIP Survivable Remote Site Telephony Feature?

Actualy we r using SIP IP phones & 2801 router(as Gateway) & SIP Server(at remote location)

So I need to config 2801 as SIP SRST(as a Back up Link)

So can u pls thru sum light on dis ASAP

Appreciate ur prompt response



sanjeevreddyallala Tue, 04/20/2010 - 05:28
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Dear Arif,

I am bit confused with the scenario or maybe I am not aware of this kind of design.

1. As I understand you have CUCM on central site and a ISR GW on remote site.

2. Remote IP phones(non-cisco) registered with CUCM as SIP rather than SCCP

3. If CUCM goes down the Remote phones needs to survive on cisco 2801 router i.e. SRST

4. at the same time they need to register with a SIP server located somewhere in internet forexample skype to make calls over internet rather than PSTN

5. means On remote site u have one physical link to central site and another(DSL) link to internet but no PSTN line at all for emergency calls?

Arifuddinkhaja Tue, 04/20/2010 - 06:19
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Dear Sanjeev

Thanx 4 ur concern. Actualy v r having a DSL Router with one ATM int which is connected to our DSL line(PSTN)

IP phones--> Gateway(Netgear Switch) --> Router(Connected to DSL(ATM int)) --> ISP --> SIP SERVER

According to my scenario if my WAN link fails or if my SIP Server goes down then I wud not be able to make calls. So I wud lyk to Config my Router as SRST i.e as a Backup link, so whnevr my WAN link goes down I wud be able make calls using my Router to PSTN..

So can u pls if posble send me da complete sample config ASAP....

Hop 2 hear u soon


Arifuddinkhaja Tue, 04/20/2010 - 06:32
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Dear Sanjeev

Do v need to have SRST feature license in the Router to enable the Cisco SIP SRST feature??


harisivaji Wed, 04/21/2010 - 07:01
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Yes its need Feature license


This PDF has all info what u required

ie, in page number 14 under "Prerequisites for Configuring Cisco Unified SIP SRST"

An SRST feature license is required to enable the Cisco Unified SIP SRST feature

As sanjeev described basic SCCP related stuffs, the same thing can be done on SIP also with slite modifications




Ayodeji Okanlawon Tue, 04/20/2010 - 03:42
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    2017 IP Telephony


You should not have that gateway in your hands if you do not know how to configure SRST. I suggest you or your company get someone with the required skill to do this job. If you are willing to learn then go on google and search for how to configure SRTS on cisco routers


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