A list of identities can be added and they will be re-gistered
and re-registered. The manager can be asked which of the of the
identities are available. This is understood as being registered.
The initial message needs to be one that is specified in GSM 08.08. We
do not support all of the messages yet but it is a start. On top of that
we also support to start with a CC Setup message.
The role of the authenticator is to collect information about
the subscriber and allow the GSMProcessor to accept the service,
enable encryptionor whatever is needed.