Files with pbb extension can be mostly found as older backup of phonebook exported from the mobile phones.
PBB file extension - Mobile phonebook data
What is pbb file? How to open pbb files?
File extension pbb is used in many mobile phones for phonebook files.
The pbb files usually contain backup created with the export function of the phone. These files can be used to restore the settings and phonebooks back to the phone.
This pbb file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.