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Choosing a Telephony Platform

Page history last edited by Wibbly 14 years ago

As of Adhearsion 0.8.0, two telephony platforms are supported: Asterisk, and FreeSwitch. This page helps you choose the appropriate telephony platform, how to install it, and how to configure it with Adhearsion.





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.




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




  • 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 is one of the new kids on the block in the telephony platform scene. While FreeSwitch does run in many production environments as a key piece of infrastructure, real-world deployment experiences have shown that the fringe features are still buggy and the available documentation is either misleading or non-existent. With this being said, FreeSwitch allows third-party applications much deeper access to the telephony platform's internals, an ideal case for Adhearsion or any other complex application logic.


Freeswitch's project direction also differs significantly from Asterisk. While Asterisk bundles together many pre-built functions for programmers' use, FreeSwitch allows only low-level remote access with very little pre-built functionality.




  • Highly modular
  • Fresher, more consistent codebase (in most cases)
  • Extensive use of third-party libraries
  • High performance. Under best-case conditions, can handle up to 2,500 simultaneous calls on a single machine



  • Considered early beta
  • Only a small subset of the Adhearsion dialplan language works with Freeswitch today
  • Poor and outdated documentation. No book.
  • Very few (any?) consultancies support it
  • Constantly changing
  • Configuration language still terribly designed (invalid XML)


Other Platforms


If you have a legacy installation of Call Weaver (aka ~OpenPBX), you may be able to use Adhearsion without problems. Call Weaver is a fork of version 1.2 and should have all the necessary AGI and dialplan applications, though it is by no means supported officially by Adhearsion.


Other projects such as Trixbox (formerly Asterisk@Home) and FreePBX are actually built on top of Asterisk and are Adhearsion-compatible, though only the vanilla version of Asterisk is officially supported. To configure these with Adhearsion, you will need to create a new context in extensions.conf which points to Adhearsion (per the Asterisk instructions) and re-map your SIP, IAX or Zap account definitions to the new context. None of these manual modifications are supported by these third-party Asterisk platforms.



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