Please note the min. version of the SwyxIt! client in the release notes for the SwyxWare 12.31 release.
Usually we offer a backwards compatibility from a major version (version 12.x can also be used with SwyxIt! 11.x) to the previously released major version.
SwyxIt! clients with a version >= 12.12 will work with restrictions on a SwyxWare 12.31. Errors in call journal or in Swyx Messenger are possible, therefore it is advisable to keep the phase between server and client update as short as possible.
Please keep this in mind when updating the server version.