As of Adhearsion 0.8.0, two telephony platforms are supported, Asterisk, and FreeSwitch. This page is intended to provide some guidance as to which platform is appropriate for which tasks.

Note: FreePBX, a fork of Asterisk 1.2, would probably work with Adhearsion, but to my knowledge, has not be tried

Asterisk

Asterisk is currently the most popular open-source telephony platform in existence. There are thousands of production deployments using Asterisk, handling millions of minutes a month. Documentation is plentiful, and consultants can be easily had all around the globe. However, as one of the oldest telephony projects, it also has limitations incurred by its large, complex codebase.

Pros:

• Well documented
• Plentiful support
• Large number of pbx applications implemented
• Wide range of implementations, from embedded devices to telco backbones

Cons:

• Monstrous code base
• Less than stellar performance (200-250 simultaneous calls per box)
• Crufty dial plan language (think BASIC-style programming, with the legibility of Perl)
• Contributors must cede copyright to Digium

FreeSwitch

FreeSwitch is the new kid on the block (or one of them, at least). While there exists a decent amount of documentation, it cannot be compared to the quantity of information available on Asterisk. Also, while FreeSwitch does run in many production environments as a key piece of infrastructure, it does not have quite the "tried and true" reputation that Asterisk has, being a much younger project.

Pros:

• Highly modular
• Fresher, more consistent codebase
• High performance (reports of 2500+ calls on a single server)

Cons:

• Less documentation available
• Fewer consultancies will support it
• Less implemented pbx functionality