About -> Available Versions -> Release 1.9.x

OpenSIPS 1.9.0 is the latest stable release. It is recommended for production usage.

OpenSIPS 1.9.1 is the latest release from 1.9 branch.

1.  OpenSIPS 1.9.1

Minor release (see Changelog from 1.9.1)
Release date: 8th of May 2013

2.  OpenSIPS 1.9.0

Major release
Release date: 27th of February 2013.