Thinking about Polycom CMA Desktop

This post continues the journey to figure out how to get videoconferencing in the 21st century classrooms in our county. Remember my original vision from 2008 as well. The other tool that is really catching my attention is Polycom’s CMA Desktop.

When I first learned about Polycom CMA Desktop, it had two drawbacks: the requirement to be on the same network as the CMA server (via VPN or physically), and it didn’t work on the Mac. Both of these have since been resolved.

In the month of March, thanks to Aaron Schippert at Saginaw ISD, I was able to play with the Polycom CMA Desktop and I’m really quite excited about it. I’m thinking in particular of two of my districts installing interactive whiteboards in all their classrooms, and wanting VC in every classroom if it can be done well.

I’m also thinking of my schools that still don’t have VC, as well as participants from my March session of Planning Interactive Curriculum Connections who were using only Skype. Once they learned what they were missing in H323 content, they were so eager to get H323 VC, but funding is a huge problem. One of the participants had set up a Skype cart for their school. What if, for a small fee, they could get H323 VC on their Skype cart as well??!!

So here’s my thoughts from testing and learning about Polycom CMA Desktop:


  • It’s super easy like Skype. It has your contact list and an easy call button. It will call an IP address or another person (by name) registered to the CMA server.
  • No echo! Echo cancellation is built in. In our test, we didn’t have to install an additional mic. Polycom CMA Desktop used the audio from the Logitech camera. With no echo. (Better than Skype! I’ve heard a lot of echos on Skype calls!) Echo cancellation is a huge issue when trying to morph desktop VC to work in a classroom.
  • Quality. In my initial tests with a login from Saginaw ISD, the video and audio is GREAT!
  • Scalability and cost. The cost structure is definitely a pro. After investing in the server, you can have unlimited downloads of the client software!!!  Of course, depending on how many licenses you buy (100, 200, 400, 500, & up), you can only have that many people logged in at the same time; and a slightly smaller percentage of those actually in a call at a time depending on setup. But teachers aren’t going to use VC all the time, so if you can just have them logout when they aren’t using it, this resource could stretch a LONG ways in education! Especially if you figure from the 10% use as normal use of VC – which I think is pretty close to a reasonable number when looking at the most VCs I have at the same time and how many codecs I support.
  • It works on the Mac! (starting April 30). Yay! This of course is critical. Not interested without Mac support.
  • When installed with a Video Border Proxy (VBP), it works great across firewalls. No configuration changes to the firewall! I tested a login borrowed from Saginaw ISD while they had a demo VBP at their site. We installed it on a PC behind our firewall, hooked up a 3+ year old Logitech camera, logged in, and we were up and running. Beautiful. Connected fine to several H323 units off our network. No problem. (Note: I understand from talking our sales guys at Polycom that this may not work as well with corporate high security firewalls. In that scenario they recommend a VBP at each network edge.) Just imagine giving an author or expert a temporary login so they can come in via H323! I’ve learned that the reason this works is the new h.460 extension to the h.323 standard. It allows the server to set up a secure connection with the desktop to easily traverse the firewall. Note also that without the VBP, each user off the network has to VPN to connect to the CMA server. Not a good solution in our scenario.
  • Dialing. Another benefit of installing with the VBP is the dialing benefits. I’ve learned that gatekeepers really do help with dialing. For example, if a VBP is installed with the Polycom RMX, the Tandberg bridge can dial in with the alias@IP format (using the VBP’s IP). I wasn’t able to actually test this, but I was told that Polycom endpoints off our network could dial in to a Polycom CMA Desktop user with the IP##alias format; and Tandberg endpoints off our network could dial in with the alias@IP format. This means that I could call out to a classroom involved in a VC, and the teacher would only have to have the computer on and logged into CMA Desktop. I have several districts where they need this level of support. Dialing in/out via H323 is another essential feature for our use of videoconferencing.


  • H.239. As I got excited and started talking to my districts interested in VC in every classroom, they wanted to be able to share the computer. That means H.239 with Polycom CMA Desktop. If you’ve been reading my blog, you know I never use H.239 if I can help it, and I find it incredibly frustrating. There are too many situations where it fails. With a regular unit, that is easily solved by zooming the camera in on the laptop. But how would that work when the laptop IS your VC system? After learning how LifeSize handles H.239 last week, my expectations were raised. I thought I’d test to see how CMA Desktop works when sharing content with the other site having H.239 turned off. Just as expected, it did not allow sending content to Polycom MGC, Tandberg bridge, Codian bridge, Tandberg MXP endpoints all with H.239 turned off. The anomaly was my Polycom VSX 7000 (version which accepted H.239 content whether or not H.239 was turned on, but that must be a fluke. So now I have to decide how critical desktop sharing is to my dream. I don’t want teachers to spend classroom time preparing a presentation and then find out the partner class can’t receive it. Note to Polycom, in a future version, when CMA Desktop detects the other site can’t receive content, could it just send the computer screen and not the webcam? Please!
  • So far that’s all I can think of for a con. What about you?

Hmm. If H.239 didn’t work with the partner school, what about taking the little webcam and facing it to the laptop screen? For that matter the webcam could serve as a document camera by moving it around too. I’ll have to think about this more.

Server Based VC

Initially in my interest in morphing desktop VC for the classroom, I wasn’t interested in server based videoconferencing. I keep thinking of the schools that install Polycom PVX and are up and running tolerably well. It is such a low cost entry starting place. How would they get started without that? Of course PVX is painful to get working through the firewall. But still, it’s an easy low cost starting place (read a success story here).

As I’ve learned more, though, I understand that Skype works so well because it too is using a “server” – a distributed system/server of course – but still it’s not stand alone. It’s the server that helps make the VC on the desktop so super easy.

So, now I’m thinking, educational service agencies or others could offer a service to schools to get access to Polycom CMA Desktop for less than the cost of the school/district getting their own server. This way tiny schools that want to start with H323 VC could get started without investing in a $8K cart or their own server. Then as they have funds they could upgrade to a full codec/cart once they saw the benefits of additional peripherals and quality.

Dr. Phil’s Choice

While I was thinking about this whole issue in March, I ran across this article on how Dr. Phil switched from Skype to Polycom CMA Desktop (and other endpoints/infastructure). Very very interesting!


This post concludes (for now) my little journey into desktop VC. I realize some glaring omissions include LifeSize Desktop and Tandberg Movi. But I don’t know any K12 people who have an installation that I could play with and learn about in an unbiased fashion. Plus spring break is about over and I’m about to get sucked into the last 2 months of busy VCs for the school year. So feel free to comment if you have anything to add to this thread and I’ll try to add more to it later. Maybe at the ISTE playground in June I’ll get more info to share. I also was awarded a SmartBoard with all the trimmings with the MACUL Educator of the Year award, and once that is installed, I will be playing further to see what could possibly work. That’s a summer project too.

Thanks, everyone for your comments and questions as we all learn together!

Full disclosure: Polycom funds the Berrien RESA VC Content Provider Database. They also link to my blog. However, they do not dictate, edit, or pre-approve anything I write here.

0 replies on “Thinking about Polycom CMA Desktop”

  1. Thanks for the review. I saw the press release recently about the updates to CMA and wondered how it would work for our schools.

      • Great question, Marty…. the other site MIGHT have it turned on, but it might also have it turned off, or even not support it. You’d be surprised at how many old units we still connect to – Vtel – yikes! 🙂 – some really really old Sony’s, etc.

        So the bottom line is, we don’t ask whether someone has H.239 or not when we pick them for a partner videoconference project. And teachers don’t want to prep an amazing PPT for collaboration like MysteryQuest or HistoryQuest and then have one of the sites not able to receive it. That turns them off to VC super fast. So my solution is, never use H.239 unless we absolutely have to and are able to test it ahead of time.

        This year out of 800 VCs we’ve had maybe 3 where we had H.239 and it worked.

        Does that help clarify?


      • I should also add that I think H.239 is GREAT for connections within your network – i.e. meetings, professional development, and shared classes. BUT, we hardly do any of that use of VC. We connect to every kind of H323 unit under the sun all over the world! 🙂

  2. We recently deployed Scopia Desktop here in LA County and it has been working great so far. I love going to a school that we’ve never been to before and we are able to simply point the browser to Scopia Desktop and with a click of a mouse they are in a videoconference with someone connected via a H.323 room system. We don’t have to worry about firewalls or opening up ports to allow the video traffic. Have you tried Scopia Desktop, and if so, how does it compare to CMA?

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