Convert NBU to VCF

Converting Nokia Phone Backup Files directly to vCard Files (.nbu to .vcf conversion) is certainly doable and typically relates to users attempts to recover their contacts data from older Nokia backup files. 

Use some of the available Nokia programs, such as Noki or the NbuExplorer, which allow users to extract/export contacts data from .nbu backup files. These can then be saved in, for instance, .csv or .vcf formats.