Before we get into the main topic of this post, I want to update you on a development. A while back I wrote about Cisco Mobile, a softphone application for the iPhone. One commenter asked about multitasking; keeping Cisco Mobile in the background while you used another app or feature on the phone. Things have changed since then. We have a couple of new versions of iOS which support multitasking. Cisco Mobile version 8.1 was also released and, according to the release notes, now supports multitasking. So if you were waiting for this feature, it arrived.
Now, onto the main topic. A colleague emailed me this week regarding Call Control Discovery. I thought it would a good topic to blog about. For a moment, let’s imagine you’re a multi-national organization. For any number of technical, organizational, and regulatory reasons you have several Cisco Unified Communications Manager clusters. You might also have deployed Cisco Unified Communications Manager Express at your smaller sites. Each of these call control systems acts independently; they know nothing of each other unless you tell them about each other.
For many years, we wished for the voice networking equivalent of the routing protocols our routers so enjoy. But without such an animal, we were left with very few choices. One option is to set up a gatekeeper and build a gatekeeper controlled truck from each of the call control systems (CUCM or CUCME) to the gatekeeper. In addition to bandwidth management, the gatekeeper can handle address resolution. When a new range of numbers is added at a site, a single update to the gatekeeper causes those numbers to be reachable by any of the call control systems.
Another option is to build a full mesh of H.323 or SIP trunks. This solution works well if you don’t have to worry about bandwidth management. But any change in the dial plan might require adjustments to all the call control agents. This makes the gatekeeper a more desirable option for most deployments.
All of that (like the lack of multitasking with Cisco Mobile) may well be a thing of the past. If you thumb through the CUCM Features & Services Guide, you find a section about Call Control Discovery. At the risk of oversimplifying things, CCD is the voice routing protocol that allows call control agents to discover one another, advertise the directory number patterns connected, and block some learned patterns if required. If you’re using E.164 numbering (see a previous post on this topic), you’ll find there’s not a lot of work required to set up this feature.
The only issue you might encounter is that this service does take advantage of Cisco’s Service Advertisement Framework (“SAF”). It’s possible your underlying network isn’t enabled or configured for this feature. Like any other feature, you should always read not only the documentation in the manuals, but also your release notes, and check the Cisco Bug Toolkit for any known interactions between the versions of CUCM / IOS and the CCD/SAF features.