Asterisk is famous for giving small shops and home users sophisticated VoIP services at a low cost. But it is also an enterprise power tool. Enterprise deployments can be daunting and tricky, so what's a big shop to do? One option is to turn to an outside expert. I had a conversation with the fine folks at NeoPhonetics; cofounder and CEO Chad Agate, and Leo Smith, General Counsel & Business Development Director, and learned some interesting approaches to large deployments.
Until March 2007, NeoPhonetics was named SIPBox. They are a Digium-Asterisk Premier Solution Partner. NeoPhonetics targets large customers: Fortune 500 and 1000, and educational institutions. School districts and college campuses are great examples of tricky distributed deployments, and also great examples of what can be done with Asterisk.
What users get
Users get all the usual goodies available in Asterisk: voicemail, automatic voicemail-to-email, call transfer/parking/forwarding, instant messaging, paging, distinctive ring on shared phones, voicemail groups, and whatever other features their network overlords deem necessary. Users manage their own extensions via a Web interface, which I think should go in the Top 5 list of "Reasons to Use an iPBX Instead of a Traditional PBX." It's a lot easier than hunting down the secret PBX codes and then entering them on a telephone dialpad.
What network administrators get
As much as or as little technical assistance as you want, a single management interface for your entire VoIP kingdom, and training for both users and admins.
NeoPhonetics aims to deliver a complete service, starting with an assessment of the customer's network. Most VoIP problems, especially poor call quality, are caused by network problems. There might not be enough bandwidth, or funky routers and cheap switches, misconfigurations, and so on. Data traffic can survive all kinds of network deficiencies; in fact, that's what the TCP protocol is designed forto reliably move data over unreliable networks. But for voice and video traffic, you need your network to be as clean and trouble-free as possible.
Once the assessment is completed, the next task is bringing the network up to a standard that will support good VoIP. This part can get a bit gnarlyyou may need to upgrade some gear. For example, replacing dumb switches with managed switches. Now that managed switches have dropped down into affordable price ranges you ought to consider retiring any dumb switches lurking in your network anyway; you'll get a lot of useful, time-saving, everyday functionality. (If you're still using hubs, for gosh sakes please do join the 21st century.) You may need an additionalor different type ofInternet connection. Then the work of actually setting up your new Asterisk systems and IP phones begins.
So you're looking at spending a fair bit of time and energy on planning and preparation before you get to deployment, which will also take some time. So don't expect that you can call NeoPhonetics, bark out "make it so," and it will happen magically overnight. On the other hand the NeoPhonetics folks know their stuff, so it won't become your life's work, either.
No single point of failure
NeoPhonetics adds their own custom management server: the UMS server. This is a wrapper on top of Asterisk that adds a lot of useful functionality. Suppose you have a network of six Asterisk servers at six different locations. With UMS you have a single management interface for all servers.
Suppose bad things happen, as they are wont to do, and three of your servers go off-line. One option is to run in circles, scream and shout. Another possible course of action is to pour another cup of tea, connect to any of the servers that are still up, and get back to work. Dial plan and user information is distributed throughout your environment, so your remaining servers will take over the load (presumably to the limits of the hardware), so you'll experience minimal service disruption. When your other servers come back online, they will automatically be updated with any new configuration information.
Wi-Fi VoIP? Not yet
Wireless VoIP is not in the cards yet, except for testing and research. There are considerable technical challenges with the 802.11 standard: it doesn't scale, reliability is iffy, and there is no Quality of Service. (These observations apply to standard, plain vanilla Wi-Fi infrastructure. Some of the proprietary, centrally managed systems cope better with VoIP.)
Cell phones, however (CDMA or GSM) are being incorporated into VoIP networks, if you really must be free as a bird and yet still tethered to your network.
Extra resources for schools
If you visit VoIP Resources > Schools you'll find information about the E-Rate program. This is a Federal Communications Commission fund that originally helped schools and library pay for Internet connectivity and telecommunications. It has been expanded to include VoIP equipment and services. As with any government funding you must jump through the exactly correct hoops in the exactly correct fashion, so pay a lot of attention to getting your application done correctly. This fund will pay up to 80 percent of your costs.