Support of version 1507 ended on May 9, 2017. As of August 2, 2016, the Threshold 1 release is the only available release in Long Term Servicing Branch (LTSB). The final release was made available to Windows Insiders on July 15, 2015, followed by a public release on July 29, 2015. It has been retroactively named 'version 1507' by Microsoft per its naming conventions for future stable releases of the operating system. It carries the build number 0 while Microsoft has stated that there was no designated 'RTM' build of Windows 10, 10240 has been described as an RTM build by various media outlets.
Windows 10 Version 1507 (build 0), codenamed ' Threshold 1', is the first release of Windows 10. 1.5 Version 1709 (Fall Creators Update).