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Why VCS has to be integrated to CUCM?

I heard that the VCS itself can route the video calls between the endpoints(tandberg, polycom, etc.). Then  what is the purpose of integrating VCS with CUCM?


Needs to be integrated with CUCM if you want to intergrate other SIP based services with your telepresence deployment; i.e. telephony services, Jabber (not to be confused with JabberVideo) etc.

Cisco is pushing more and more for users to move to SIP and have call admission control (CAC) handled by CUCM, with VCS-C doing the same for H.323 specific applications, and the Expressway doing firewall traversal for both.

Stupid thing is, if you register a SX20 to CUCM, then H.323 is disabled on the end-point, so now it's SIP only - whereas if you register it with a VCS-C, then you can register it with dual stack; both SIP and H.323.


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The question is if you really need that.


If you register your endpoint to CUCM you should not have it connected to a second call controll

anyhow, so thats fine and not stupid :-)

Also if you need some interop with h323 you will possibly need an additional

address space in your dialplan and just keep that stuff on a VCS till you aged it out with CUCM

capable devices.


Jens: did you check on the SX10 and SX80? You will love them:

SX10=SIP only

SX80=either or (if you add any kind of sip settings h323 is gone.



Anyhow, moving to sip as the default call protocol should work for most endpoints,

moving them to cucm shold work for many as well.

The C-Series is also more than 5 years old and they are fine, natively to CUCM

MXP with F9.3 should work fine with SIP on the VCS as well.

Then there is not that much left with h323 only which needs to be interworked (which the

VCS is anyhow doing a great job).

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"SX80=either or (if you add any kind of sip settings h323 is gone"

And therein lies the problem - we need to be able to use both H.323 and SIP as we deal with a lot of external parties who are either SIP only, H.323 only - or like us, supports both protocols.

Yes, I know I can interwork these on the VCS-E, and that works fine in a lot of cases, but not so fine in some cases...allbeit a minority, but still enough to generate complaints which we can do without.

I personally see no big issues with using two different CAC devices for two different protocols - well, at least not for us. Guess what I'm really objecting to is not having the option to do what we want to, and how we want to do it, and instead having this forced upon us by Cisco.


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Same here, we use SIP for internal connections to CUCM. And for external calls we use H323, as for us, nobody is opening SIP.


If you rent a video conference room, or if you want to connect to a customer video device, it is always copper or H323, never SIP.


Due to this limitation of TC endpoints (we use SX20), we need to create/get a white elephant, that's a pitty...


I rarely see ISDN connectivity anymore and even the VCS setups are all SIP enabled. Its not only Cisco pushing sip, its more or less what all bigger vendors use by today.


Which country are you in and what kind of business are the external parties you communicate with?


Which limitation do you see on the SX20? That can be used dual stack (sip and/or h323). It also works with CUCM, VCS or standalone.


I also do not get what you mean by "white elephant"


I would not recommend to stick or even deploy a VCS only deployment, but that also

works great with SX10 or SX80. The VCS will translate in between SIP and H323 so even if everything internally is registered sip only you could have  h323 only external


What I strongly recommend you to do for the future is to look into CUCM.

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saddly, I guess for security reason, some customers only allow ISDN access for third parties, and reserver IP (SIP or H323) for internal calls.


Anyway, today, we never "saw" a company asking for SIP access. When we need to setup a video conf, it is always direct H323.

Our Polycoms are fine with this, raw H323 setup for best quality inside the company with other Polycom and external access, and SIP setup to our CUCM for connection to PSTN and phone devices like the 9951 with camera.


As we're going to move to CUCM10.5, our partner wants us to connect our Polycom to VCS instead of direct registration to CUCM.

And our SX20, should be natively managed by the new version of CUCM. In this case, the H323 stack will be disabled. And of course, we would have prefered to keep H323 in addition to SIP.

It is hard to see the value added of VCS and "SIP only" sx20, and it is harder to sell to management the added cost.

BTW, intially we removed from quotations SX10 due to the no support of H323 :(


VIP Advisor

As others have mentioned, the VCS doesn't have to be integrated with a CUCM.

You'll integrate it with a CUCM when you want to start to talk to and from other telephony devices (your IP desk phone, Jabber client, etc).

If you want to have all your video infrastructure seperate you can, and then don't even need to own a CUCM.

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