Default Change device / ROM without change BBM PIN

- First install TITANIUM BACKUP (TB) from Play Store,

- Open TB, than backup BBM

- Copy backup folder "/sdcard/titanium backup" to external or USB storage

- After you change device / ROM, install TB again

- Copy back folder "/titanium backup" from your temporary disk to "/sdcard/"

- Open TB, restore BBM choose "App+data"

- Done.