Glossary

Mobile handset software architectures are usually separated at their core into two basic layers: baseband and application. The baseband layer tends to be implemented over proprietary or low-level operating systems, while the applications and GUI layers tend to be implemented using higher level operating systems, such as Embedded Linux, Android, Windows Mobile or Symbian.

In order to connect the baseband to the applications and allow communication flows between the cellular network and the user's interface, a logical layer called RIL is used. This layer exists in the architectures of most modern mobile operating systems and requires tight integration between the operating system and the baseband chip used.

For example, Windows Mobile RIL is managed using TAPI (Telephony APIs). In Android, RIL is managed using a RIL Daemon, which connects to a Vendor RIL that is developed and modified by the baseband supplier or the handset vendor itself.