What’s the difference between CallManager and CallManager Express

Many people have asked me the difference between Cisco CallManager (CCM) and Cisco CallManager Express (CME). The answer is not that complicated but can be somewhat confusing and understandably so. Most software companies offer an "Express" version of their software where they have reduced the feature set or scalability of the product and therefore the price to make it more viable for smaller businesses. However, in this case, these two products are entirely different platforms, each with their own strengths.

CallManager is a server based product, now referred to by Cisco as an "appliance". It's basically an HP or IBM server with the a hardened Linux OS with the CallManager software bundled into it. Appliance is a good description of it since you basically just manage it through the web interface and even if you were to login to it at the console level you would only get the customized administrative shell with no access to the underlying OS.

CallManager Express on the other hand is IOS based meaning that it runs on a router, specifically any of the ISR 2800/3800 or the ISR-G2 2900/3900 series routers. They are really amazing boxes as they can literally bundle all network & voice services into one platform. For example, you could deploy a small office with Firewall/VPN/DHCP/PBX/Voicemail/Switching in one box and even throw in redundant WAN connections if you were so inclined. They support traditional PSTN connectivity such as PRI/FXO as well as IP trunks such as SIP or H323. Multiple offices can be interconnected providing 4 digit dialing between sites/offices or for least cost call routing.

Both of these products have been on a very aggressive development roadmap. CallManager is now the IP PBX of choice for enterprises or anyone with a Cisco network. It has the full complement of enterprise features with the scalability and redundancy you would expect. It is really impressive. Similarly, CME has come a long way since it's early days where it did very little other than provide basic voice services (dial tone). It can now provide a full set of features including Single Number Reach, advanced call routing, advanced conferencing, and supplementary services. Both systems use the same phones and provide similar user experience.

The primary difference is in scalability and redundancy. CallManager was designed for the large enterprise market. The system can be designed with multiple levels of redundancy for call routing and fail over such that there would be no single point of failure and could survive multiple failures if that level was required. CallManager are deployed in clusters and can support up to 30,000 phones per cluster. Clusters can be inter-connected to provide a seamless voice system. CME on the other hand was designed to be a single site solution and it excels at that. Some enterprises actually use a combination of the two solutions and inter-connect them with IP trunks. It is also very good for some businesses where network management is localized vs. centralized.

Feature wise the CallManager is king. Administrators have very granular control over call routing. Since we are in the IP world the CallManager software is developed much faster. Cisco makes some additional products (Presence Server/WebEx Connect/Meeting Place/PC based Attendant Console) that can integrate into the CallManager to provide enhanced services. And that goes for third-party software as well. This is a weakness of CME, there is very little additional software support for it.

One exception to this today is a relatively new product called CallManager Business Edition which is an appliance (server) but has limited scalability (500 phones and 20 sites). It is a single server solution and has a price point lower than a CallManager cluster and just a little bit more than CME.

So your choice of these options will be based on design and features required. The design should be put together by whoever is in the role of the network architect while the features should be addressed by the Systems Administrators. Both these individuals should work together and solicit input from managers and executives. The reality in small businesses is that these roles are often rolled up into one person. On the plus side, all of these options upgrade smoothly into the next level. For example a CME router would just turn into a voice gateway and a Business Edition appliance could upgrade the software to CallManager providing an unparalleled level of investment protection.

Cisco's recommendation for any customer is to consult with Cisco Partner and that is a sound strategy.