scope:

This European Telecommunication Standard (ETS) specifies the network functions needed to provide the security related service and functions specified in GSM 02.09. This ETS does not address the cryptological algorithms that are needed to provide different security related features. This topic is addressed in annex C. Wherever a cryptological algorithm or mechanism is needed, this is signalled with a reference to annex C. The references refers only to functionalities, and some algorithms may be identical or use common hardware.