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Gatekeeper direct calls



We have a customer with h323 videophones who wish to call one of our extensions directly. So I am trying to find out whether it's possible to call a gatekeeper endpoint from an external h323 video endpoint (not registered to this GK). Or to simplify my question, is it possible to call GK extensions without a registartion? If so, in what format the call would be initiated, is it extension@gatekeeper_ip?

Thanks in advance.


11 Replies 11

William Bell


What gatekeeper platform are you considering?  The Cisco VCS (from the Tandberg acquisition) can address ingress dialing from endpoints not registered to the VCS gatekeeper. There are three methods:

1. Inbound URI dialing. If the remote endpoint supports H.323v5 Annex O then it can dial other endpoints using an alias similar to a SIP URI. In H.323 it is called an alias URL (I believe). An example: In addition to the endpoint supporting H323 Annex O, you will need to have NAPTR and SRV records defined which allows the endpoint to resolve the domain (, for example) to the IP address of your VCS.

2. ENUM dialing. Leverage ENUM services in DNS, an endpoint can resolve an E.164 number to a DNS name. Again, requires specific DNS configurations.

3. Fallback alias. A VCS can be configured to accept any calls directed to its IP address by substituting an alias. This would normally be used to direct callers to a video attendant (IVR) where they would then be able to enter an extension they would like to reach.

I am not sure if gatekeeper IOS has similar functionality or not. I have used IOS gatekeepers for voice primarily and some internal video call routing (many moons ago). Cisco has other products which can provide GK functionality (including some of the Codian series products inherited with Tandberg). I have avoided using such GK functions in the past. Usually, they don't scale so well. I am not sure CVMS is even a product anymore.




HTH -Bill (b) (t) @ucguerrilla

Please remember to rate helpful responses and identify


You can, in addition to the options already given, use Alias@GK_IP_address,


Sent from Cisco Technical Support iPhone App

Thanks guys for your advice. We are using Cisco IOS GK here. So I am still not sure whether it will accept these calls.

The customer has been trying to dial us using format extension@GK_IP_address. However, for some reason their system tries to route it via an internal trunk to CallManager.

They are using Tandberg edge T95 endpoints and Tandberg GK.

How about they neighbour their GK to yours - then perhaps add a prefix for calls to systems registered to your GK, i.e. if your system has alias 12345678 they dial #012345678 - which points the call to your GK only, they'll need to strip the prefix though.

cheers jens

Unfortunately it's a bit complicated due to thier internal procedures... that would take too long.

But I am waiting to hear from them for some more tests. I will keep you posted.



Just a thought, have they actually turned on URI dialling on the TANDBERG GK ?


This is a good question... I don't know. So this should be activated on GK, not on the endpoint? I thought that endpoint detects when URL is entered and contacts the remote party directly?

Yes - and no

If their Edge is registered to their TB GK, then they need to enable URI dialling on the GK;

using CLI: xConfiguration Gatekeeper DNSResolution Mode:

(set this to On)

through web interface: go to Gatekeeper Configuration --> Gatekeeper, tick the box next to "Allow DNS resolution".

(At least one DNS server address has to be configured for the GK to query).

If their Edge is not registered to their TB GK, then the call set-up mode should be set to "Direct", and URI dialling should "just work" .

Not sure about how the Call Manager affects this though as we don't use one, we did use the TB GK and BC for quite a while, but we're now running VCS-C's and VCS-E.

cheers jens

Davide Fiumi


If endpoint A (H.323 device not capable of URI  dialing) wants to directly call Johno Doe's device registered onto VCS, then the first endpoint can dial:

  will see called alias "john.doe", so if a translation rule exists which  appends the SIP domain to destinations without any:

          Pattern: ([^@]*)

          Replace: \

Then the call will be directed to

Tested on VCS X6.0



Filippo Zangheri

Hi Filippo,

At the moment we are at the stage of completing the migration to SIP plaform. So I won't be able to test your instructions. In any case thank you for your help.

"If endpoint A (H.323 device not capable of URI  dialing) wants to  directly call Johno Doe's device registered onto VCS, then  the first endpoint can dial:

   will see called alias "john.doe", so if a translation rule exists  which  appends the SIP domain to destinations without any:

          Pattern: ([^@]*)

          Replace: \

Then the call will be directed to

Tested on VCS X6.0"

Just be aware IP_address##Alias or domain##Alias is PLCM proprietary "URI dialing" and will not work from a TANDBERG/Cisco end-point.

And yes, your pre-search transform works - I've been using a similar one myself for a while now (currently on x7.03) to allow older Polycom end-points to connect into our networks.


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