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No available DNs, maximum 100


When we add a new conference on MSE8510(Ver4.2), an error message below was outputted.

(The conference was added on the MSE8510)

Moreover the added conference wasn't registered with VCS Control, so we couldn't

connect the conference even though we dialed an E.164 number that should have

been registered with VCS.

(Event log on MSE8510)

50282  19:03:51.649   GATEKEEPER  Warning  No available DNs, maximum 100 (repeated 99 times)

We confirmed that we could call an endpoint from the conference.

We've already created almost 100 conferences on the MSE8510 with no DNS servers

but we've never seen such error message.

What does this message mean?

Is there any workaroud for this?




'DNs' in this context refers to 'Directory Numbers' rather than DNS - the MCU is capable of registering a maximum of 100 numbers with the h323 gatekeeper. If you require more than 100 MCU conferences to be accessable for people to dial in, then it would be better just to register the MCU's service prefix with the VCS and not register individual conference IDs, such that all e164 numbers starting with that prefix are routed to the MCU. You can then dial prefix+conference ID to access the conference directly.

HI Luc,

Thank you for your prompt reply.

We can see the description below on Page8 of "d1478610_cisco_telepresence_mcu_4-2-1-43_release_notes.pdf".

Increased number of conferences

The Cisco TelePresence MCU MSE 8510 can now support up to 500 conferences.

We thought this means we could create up to 500 conferences on one MSE8510 and register all of them with VCS Control.

But you mean actually we can create up to 500 conferences but we can only register up to 100 conferences with VCS Control, is it right?


Yes, if you need to have a large number of conferences available for dial-in then we would reccomend using prefixes as registering each individual conference ID does not scale so well. Although the number of conferences running on the MCU has increased the same limitations around h323 registrations are still present (and there is a similar story in SIP).

If you need to do ad-hoc dial-in conferencing on a large scale then you may want to look at deploying Cisco TelePresence Conductor.

Martin Koch

Like Luke said, you do not need the "numeric ID for conferences" you can just use the prefix registration,

a prefix registration works great.

Cisco online help:

Cisco recommends that you use the Terminal / gateway option           unless you are using a service prefix (in this case, use Gateway). Only            use a different option if you are:

  • having specific problems
  • using the            VCS as a gatekeeper (with or without a service prefix), in which case use       MCU (standard)
  • using the            Cisco Gatekeeper (with or without a service prefix), in which case use Gateway (Cisco GK compatible)
  • using the            VCON MXM Gatekeeper (with or without a service prefix), in which case use MCU (compatible)

Refer to the Knowledge Base in the Support section       of the web site for more details about interoperability with gatekeepers.

The "MCU (standard)" works fine for us with in combination with the VCS, even without a TP Conductor.

What kind of gatekeeper do you use?


Please remember to rate helpful responses and identify

Thank you Luc and Martin.

I understand that more than 100 conferences per one blade can't be registerd with gatekeeper for now.

(We use cisco VCS Control as a gatekeeper)

We're using MCU service prefix and ad-hoc dial-in conferencing in our circumstance.

But we thought if we could register more than 100 conferences with gatekeeper, it would be greater help for us

and our customer.

Because we have hundreds of endpoints and some of those are SIP endpoints that can't use SIP registrar.

(That means those SIP endpoints can't use prefix)

So those SIP endpoints need the procedure below to dial in ad-hoc conferences.

1.Dial to Auto attendant of MCU.

2.Enter an ad-hoc conference numeric ID.

   If other participants have already joined the conference, the SIP endpoints also can join the conference.

   But if NO other participants have already joined the conference, the SIP endpoints have to create a new

   conference by pressing right arrow key of remote control after they heard

   "Sorry I did not recognize that conference code.Please try again".

If we could register all of static conference numeric IDs with VCS, those SIP endpoints can join a conference without inconvenient procedure above, and other H.323 endpoints can dial using e.164 numeric ID

in the same way they used to.