Online social network services (OSNSs), such as Facebook Messenger, Email, Twitter, SMS, etc., have become an integral part of our daily lives. At the same time, the aggressive market competition has led to the emergence of multiple competing siloed OSNSs that cannot interoperate. As a consequence, people face the burden of creating and managing multiple OSNS accounts and learning how to use them, to stay connected. USNB provides interoperability between heterogeneous OSNSs, allowing people to use their favorite one to communicate…