Buyers face a bewildering array of suppliers with an even more bewildering range of features and functions. However, the benefits can be enormous: not just in cost savings and new features but in the way IP telephony can integrate with business IT applications and processes in ways that just weren't possible with an old style PBX.

The biggest decision any business contemplating an IP telephony solution faces is whether to go for a hosted or on-premises solution. The guide explains that hosted systems take most of the switching and intelligence of the system and move it offsite to a remote location where it is managed by the service provider. Equipment at an organisation's site is limited to the phones themselves, some dedicated routing equipment and perhaps a switch to provide emergency access to the older traditional TDM telephone network.

It says that, as a result, "hosted systems are usually quicker and cheaper to install and set up. They offer a standardised set of services. Because they are hosted remotely, there is less maintenance for a business and no need to perform upgrades. The downside is that upgrades often must wait until the service provider is prepared to offer them. There is less flexibility and fewer options in configuring the system."

In the past it's been assumed that hosted IP PBXes are a better solution for small-to-medium-sized businesses, while premise-based solutions are better for medium to large companies. The report contends that this is no longer the case. "The new breed of premise-based PBXes hold their own very well in the market against the hosted services."

The bottom line, it says is that: "If you are upgrading from an old phone system, you will save money no matter what. The real differentiators for recommending a premise-based solution are the need for customisation, the need for full control of the system, special applications that must be enabled and the size of organisation; the larger the organisation, the more likely a premise-based solution is the right call."

To help you make that call the guide provides a check-list of the questions you should ask yourself before talking to an IP PBX supplier and a comprehensive list and explanation of the basic and advanced features offered by the typical IP PBX. There's also a feature-by feature comparison of IP PBXes from a dozen leading vendors: 3Com; Altigen, Avaya, Cisco; Digium; Fonality; Intuitive Voice; Mitel; Nortel; Pingtel; ShoreTel and Siemens.

You can download the guide and the vendor comparison chart at no charge, here.