BBM was different since the PIN was baked into the device so it as more seamless than even using your phone number. The problem was when you change your device

BBM was different since the PIN was baked into the device so it as more seamless than even using your phone number. The problem was when you change your device you can't migrate your PIN so I think it contributed to decline to usage as people moved to other BB devices or iOS/Android This only strengths the argument why majority of chat apps use phone number as your username.