Solved: SRST Question.

opnineopnine · ‎07-30-2015

hi all,

I have a GW configured with srst I have to migrate this GW to a different location, but in this new location, the Internet access will not be enabled yet, my question is, when I connect all connected, will this phone go to srst mode? or I have to force them to srst?

thanks.

Wilson Samuel · ‎07-30-2015

So, if you are keeping all the configurations same on the Router (most imp the IP Address that is configured for SRST as well as the IP Address where call-manager-fallback will respond) then all the phones will go into SRST Mode.

In fact, once configured GW are always responding to SRST queries, so even during when there is no outage, if the Phone for any reason is not able to reach the CCM Servers, it will try to reach out to SRST GW and it will register with them.

So as long as your GW and Phones are configured correctly they will fall-back to SRST Mode on the new site (till there is no WAN connection).

However the phones MUST have had registered to the CCM at least once, before they can register with SRST

More over, you could use CME till the time you do not have WAN connectivity on the site (Cisco voice bundle gw come with I think some number of CME Lic by default so that should work)

HTH

View solution in original post

iptmartinesparza · ‎07-30-2015

If they the GW can't communicate back to CUCM the phones will fall back to SRST that's if you set it up correctly. Try testing it off hours before the move.

opnineopnine · ‎07-30-2015

Hi all,

I have the GW already configured with SRST, this gateway is located in site A, I will move this GW to site B, (but it will keep all the same configuration) but in site B, there is no access to the CUCM. When I connect the GW will the phones go to SRST mode?

How can I force the GW to go in SRST?

Thanks!

Wilson Samuel · ‎07-30-2015

So, if you are keeping all the configurations same on the Router (most imp the IP Address that is configured for SRST as well as the IP Address where call-manager-fallback will respond) then all the phones will go into SRST Mode.

In fact, once configured GW are always responding to SRST queries, so even during when there is no outage, if the Phone for any reason is not able to reach the CCM Servers, it will try to reach out to SRST GW and it will register with them.

So as long as your GW and Phones are configured correctly they will fall-back to SRST Mode on the new site (till there is no WAN connection).

However the phones MUST have had registered to the CCM at least once, before they can register with SRST

More over, you could use CME till the time you do not have WAN connectivity on the site (Cisco voice bundle gw come with I think some number of CME Lic by default so that should work)

HTH

opnineopnine · ‎07-30-2015

Hello Wilson,

The last part is the one I dont get it, can explain me more about this?

Thanks.!!!

(More over, you could use CME till the time you do not have WAN connectivity on the site (Cisco voice bundle gw come with I think some number of CME Lic by default so that should work))

Wilson Samuel · ‎07-30-2015

Sure. I was saying that, if your site has supported amount of phones at location (e.g. less then 35 phones for 2901) you may configure CME to begin with and dont have to worry about for SRST kicking in or not, as CME supports more features than SRST

Please find the number of phones supported by the 2900 Routers for SRST as well as CME

Table 7. Cisco 2900 Integrated Services Router Product Specifications

	Cisco 2901	Cisco 2911	Cisco 2921	Cisco 2951
Services and Slot Density
Embedded Hardware-Based Cryptography and Acceleration	Yes	Yes	Yes	Yes
Cisco Unified SRST Sessions	35	50	100	250
Cisco Unified CCME Sessions	35	50	100	150

HTH

Wilson Samuel · ‎07-30-2015

Hi,

I am not sure I understand your question clear enough. I assume that you want to if just connected all the phones to the network and the GW, will the phones go into SRST Mode if the phones cannot reach the CUCM?

The answer is, as long as the phones have got the configuration of the SRST from the CUCM, they will be able to register with the router in SRST Mode.

Please feel free to let us know if you have any more questions

HTH