10.16.3.3. System Reactions 
For user guidance, a tone is injected after every PEN that is selected.
The following cases are discriminated:
- PEN x seizes CorNet-NQ circuit: First ring tone from the reached PBX (FRNGBK);
- PEN x seizes analog or CAS tie trunk: Dialing tone from the reached PBX, if dialing tone injection is configured for this tie trunk;
- PEN x seizes trunk circuit: The proper CO dial tone is injected;
- PEN x seizes SLMA circuit: Connection of the corresponding terminal (exception: VMX). With anate the ring tone is injected and the ring tone is injected at the calling party (RNGBK);
- PEN x seizes line circuit. The then dialed station number is not transmitted because the CTLS parameter is not set in COT (NU)
- PEN x or destination of station number is busy: busy tone (BUSY);
- PEN x is non-existent, invalid for CTLS or overdefined: NU tone is injected (NU);
- PEN x is defective/out of order: Negative acknowledgement tone (NACK);
If a station number is entered and the connection is established via transit
PBXs, these PBXs do not transmit any tones.
INFO:
When dialing a number after * to a none NQ system, the CPTIME CTLS2
to must have expired to allow dialing.