This would sound a little like hacking, but you can try to do following:
1) do backup
2) in the backup file clear the \vmail\temp\db\backup\data_save\SPEED_CALL.37 file (delete the file and create and empty SPEED_CALL.37 file)
3) restore from the updated backup file
I have not verified this in the lab is trying this method is under your risk ;-)
The format of these files is quite simple, the meaning of the extension e.g. the .37 is actually a size of each record in the file, so clearing the content of the file means 0 records in it.