SRST gateway gatekeeper with shared line

Unanswered Question
Sep 23rd, 2007
User Badges:

Hi, guys,

I am trying to implement a large remote site with no local CCM. The remote site has five SRST gateways, one of which will serve as gatekeeper. In normal status, all phones are registered with CCM, and the gateways are H.323 peer to PSTN.

During WAN outage, all phones are registered with local gateways, and the gateways will register E.164 address to gatekeeper. So it will work as a H.323 environment.

However, in the real case, the users are using shared line quite a lot and the same E.164 numbers are registered with different gateways. And ironically, one single conflict number between gateways will fail the gateway registration with gatekeeper. Is there any way to work around this technical limitation? The numbers are all over the remote site and cannot be categorized into number blocks for different gateways, so zone prefix or tech prefix does not help much in this case.

Any idea will be highly appreciated!


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Avner Izhar Sun, 09/23/2007 - 22:03
User Badges:
  • Bronze, 100 points or more


How many phones are we talking about here?

Can't they all register to one gateway?

More details about the topology, pstn interfaces and numbering plan would help to suggest alternatives.

Regards, Avner.

soupseven Mon, 09/24/2007 - 06:31
User Badges:

Thanks, Avner,

We have more than 1,000 phones in this single huge remote site. It is not possible to register all the phones into one SRST gateway. And we need some dedicated SRST gateway for some specific sub-site within the remote site. Moreover, the DNs are very scattered and cannot be grouped to gateways by blocks.

Regarding to SRST gateways, we have PRI to PSTN. DNs are registered with CCM with 10 digit.

Now what I am thinking is not to register E.164 to gatekeeper, but use the same tech prefix for all the gateways. What I am not sure is will the gatekeeper send request to all the gateways simutaneously or in a order. I may need to set priority in gatekeeper or not...

Thanks a lot for your help. It is my most complicated design and implementation so far.


Avner Izhar Mon, 09/24/2007 - 07:06
User Badges:
  • Bronze, 100 points or more

Guess clustering over the wan is not an option?

Anyways, the other option I can think of is to not register the e.164 and statically register all extension to the gatekeeper, using the 'alias static' and pointing every 10 digit number to the designated gateway. Not sure if there is a limit here or not, from the gatekeeper capabilities perspective.

Let us know if it worked, Avner.

soupseven Mon, 09/24/2007 - 07:20
User Badges:

Right. cluster-over-WAN is not an option since the round trip delay is always above 50ms.

Using 'alias static' is not practical here for over 1,000 DNs.

Thanks again. I will update my test later.


kelvin.blair Mon, 09/24/2007 - 08:42
User Badges:
  • Silver, 250 points or more

Just an idea why can't you change the SRST configuration to fallback to CME.. You have a little flexability with that type of configuration.

soupseven Mon, 09/24/2007 - 09:17
User Badges:

We have more than 240 IP phones per gateway.



kelvin.blair Mon, 09/24/2007 - 10:04
User Badges:
  • Silver, 250 points or more

Oh.. I see. Unless you have a 3845, I guss that want work. I agree with what avner is saying with the static alias statements. It will be cumbersome, but that should work.


This Discussion