Asterisk

Facts

License GNU General Public License v2.0 The GNU GPL is the most widely used free software license and has a strong copyleft requirement. When distributing derived works, the source code of the work must be made available under the same license. There are multiple variants of the GNU GPL, each with different requirements. May Commercial useModificationDistributionPrivate use Must License and copyright noticeState changesDisclose sourceSame license No LiabilityWarranty Summary from GitHub's choosealicense.com

Paid-feature tier C Tier CDaily-workflow features need a paid edition

Self-host Self-hostable: yesYou can run it on your own server.

Paid-feature limits1 noted

• Sangoma G.729 transcoding codec is licensed per concurrent channel ($8 USD listed); G.729-dependent recording, conferencing and DTMF processing require decoding rather than passthrough.

Tier C: Core Asterisk source is OSI GPLv2 with documented linking exceptions; Certified Asterisk source remains freely usable. Tier C reflects separately licensed same-vendor ordinary voice functionality: the G.729 transcoding binary is paid per channel, which affects media-processing workflows when that codec is required. This does not imply all calling requires paid modules; other codecs are available. Asterisk is a developer engine, not a turnkey business calling workspace. First-party PBXact Cloud is a separate Asterisk-derived managed PBX, not source-edition parity. Other vendor binary add-ons require their own license checks. License source. Repository: asterisk/asterisk. Self-host: server; hosted offer from the project: yes.