About -> Available Versions -> Version 2.1.x

OpenSIPS 2.1 is a stable release and can be used in production. Still, note that this branch reached the end of its life cycle and it is not maintained anymore (no more releases and no more fixes)

OpenSIPS 2.1.5

Minor release (see Changelog from 2.1.4)
Release date: 19th of October 2016

OpenSIPS 2.1.4

Minor release (see Changelog from 2.1.3)
Release date: 20th of July 2016

OpenSIPS 2.1.3

Minor release (see Changelog from 2.1.2)
Release date: 30th of May 2016

OpenSIPS 2.1.2

Minor release (see Changelog from 2.1.1)
Release date: 14th of Jan 2016

OpenSIPS 2.1.1

Minor release (see Changelog from 2.1.0)
Release date: 19th of May 2015

OpenSIPS 2.1.0

Major release
Release date: 7th of May 2015
First release candidate date: 18th of March 2015
Second release candidate date: 22nd of April 2015