Kamailio 5.1.10 stable version was released. Kamailio goal is to create an open development environment to build a robust and scalable open-source SIP server. Kamailio is a pure SIP server, it can be used as PROXY, register server, redirect server, or as a simple PRESENCE server.
This is a minor release, since v5.1.9 contains code and documentation restored to preserve compatibility configuration files and database schema, which means that users do not need to change anything to be updated.
Meanwhile, v5.1.10 is the last version of the 5.1 series, which marks the formal end of the maintenance branch 5.1, the official recommended that users upgrade to 5.2.x or 5.3.x series as soon as possible to ensure that running a supported version.
5.1.0 released at the end of 2017, about the new features of the series, you can view:
https://www.kamailio.org/w/kamailio-v5-1-0-release-notes
5.1.10 on the specific circumstances change, you can view: