You can download and use a small utility called vmsg2csv that can be used to convert SMS messages saved in .vmsg and save it as .csv files.
Convert Versit message format to Comma Separated Value.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert vmsg to csv on Windows
A converter for SMS backups
Convert from vmsg 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.