For GOS 4.3 a new patch level is available:
This release unlocks the migration from GOS 4.3 to GOS 5 for GSM ENTRY (MAVEN, ONE) and GSM SME (150, 150V) models.
For further information on GOS 5 please see the announcement at:
GOS 4.3.12 also includes various fixes for GOS 4.3 and offers several prospective performance improvements for high-load situations.
In total the patch level itself covers 11 improvements.