Some data out of BlackBerry phone backups (.bbb) can be exported and saved in XML format. Probably the case for some contacts, calendar data or perhaps email messages and other relevant data that can be saved as .xml files.
Convert BlackBerry backup (post 2012) to XML document.
We found one software available in the database for this conversion.
Microsoft Windows software - convert bbb to xml on Windows
A backup and recovery software for smartphones
Convert from bbb 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.