IuCS: postpone signalling until after ciphering
Testing for #1816 brought my attention to this:
I suspect that libmsc would in some cases attempt to send signalling
messages to the UE without verifying/waiting for ciphering.
For example, the 'subscriber * ussd-notify' command merely checks whether a subscriber
has a conn available. For 3G, ciphering is required, so this should also reject
transmission when no ciphering has been established yet.
Make sure that in UTRAN no such actions are possible without ciphering established.
It probably makes sense to check this only after the new VLR is integrated (#1592).