We tested the open source net.PBX Communications edition from Escaux. It is built on Linux Debian 2.6.18 and Asterisk 1.2 and ships preloaded on a 4U appliance with Digium analog or T-1/E-1 cards installed. Escaux also provides a free edition that can be downloaded here, along with two other retail versions: Convergence and Call Center. All editions required Internet connectivity to the hosted service-management platform (SMP) for maintenance and management purposes.

Net.PBX has a Web interface for managing the IP PBX. Escaux uses a call-flow editor to configure call routing and distribution, which can be defined as a single user or as a group of users.

We exercised some additional features offered by net.PBX, such as Mobile User Logon (a Web interface that lets you change your status and make calls) and net.Desktop, a thin Web client for a user's personal configuration tasks. The Presence Engine let us change the presence status in multiple places throughout the system no matter what device we were using. With most other systems tested, presence could be changed only in one place. Net.PBX auto provisions selected IP phones from Cisco, Polycom, Thompson, Grandstream, Swissvoice and Sipura (see How we tested IP PBX). We verified autoconfiguration with the Polycom and Grandstream phones. Included in net.PBX is an application integration module that supports integrating the underlying IP PBX with extended applications such as CRM for use in a call-center setting.

Add-on applications include an Operator Panel, which is designed to help the attendant manage incoming and outgoing calls in a desktop view. The Operator Panel was adequate, but compared with the competition, it lacks presence and a call log.

All standard IAX and SIP phones were supported but had to be manually configured. Escaux recommends that mobile SIP users use a VPN tunnel for security reasons. The alternative method is to use only IAX devices outside the security boundaries of the network. This method required one port (4569) to be opened on the firewall to connect to the IP PBX.

Escaux offers a high-availability option for the system. To test this, we configured a second IP PBX as an active-passive standby server. The passive server is updated daily with the current database by the SMP service. We simulated a catastrophic failure on the active server, and the SMP Web interface notified us so we could manually activate the standby to take over the load. This is not an automatic function; it is available for those that want this capability.