Both the .sisx and .sis files are used as installation packages for Symbian phones. Users frequently try to save one to another when they try to install apps across various versions of Symbian OS: Typically can be done with some kind of Symbian utilities like SIS to JAR converter.
Convert Symbian OS program installation executable file to Symbian installation file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert sisx to sis on Windows
A dedicated converter for Symbian packages
Convert from sisx file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.