Base Band 5

Base Band 5, abbreviated as BB5, is the youngest mobile baseband generation implemented on Nokia mobile phones and the replacement for prior DCT generations.

This generation of Nokia phone basebands uses a new range of chipsets, bus systems and components as well as enhanced security mechanims preventing manipulations on firmware and system configurations. The phones system interface has changed over from previous generations to allow a new flash concept via USB for example.

The system is designed to prevent unlocking of certain key capabilities of the handsets (such as usable network or installation of unsigned operating system), which has not been approved by Nokia or the network. Just like the DCT-4 locking system, the unlocking code is unique to each handset. However, unlike DCT-4, the unlock code is much harder to calculate as each code is randomly assigned to the handset and stored on a special chip.

In May 2007, an engineer named Dejan Kaljevic from Serbia (who earned his fame from the free DCT-3 and DCT-4 unlocking solutions), has released a free program which can unlock many of the older Nokia BB5 phones such as the Nokia 6630, Nokia 6680, Nokia 6681 and the Nokia N70. There were reports for other models include the Nokia E60, Nokia E65, Nokia E70, Nokia N71, Nokia N90, Nokia N91, Nokia N93, but was deemed to be fake, since the unlocker only supports older BB5 models. This is easily done by the end-user through the phone's Pop-port connecting a legacy FBus compatible cable such as DKU-5, to a computer running his unlocking software package. Since then, commercial unlocking solutions have been offered by some others along with successful claims on some newer Nokia BB5 phones as well.

In July 2007, Kaljevic released the instructions and schematics to build a hardware solution for unlocking the Nokia N95. It was based on a CPLD logic IC and worked by manipulating CPU instructions on-the-fly, fooling the phone that a wrong unlock code was accepted like a correct one. However, it is not designed for end-users, since it requires more advanced knowledge in electronics and soldering skills to accomplish.

In August 2008, Kaljevic released a full unlock box for newer BB5 handsets that doesn't require any soldering.