A complete IP PBX released as open source under the GNU Public License, Asterisk is built to run on commodity hardware, providing considerable cost savings when compared with commercial alternatives, and it leverages the open source community for additional testing, bug fixes, and feature development. Plus, Asterisk is available in many different forms, via GUI-simplified and support-backed packaged solutions such as Trixbox and AsteriskNOW or as raw source code, depending on your needs.
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