11.1.9.4. Service Information 
The feature is an integrated S/W solution.
After the JOIN key has been pressed, only the following keys will appear active to
the user:
- JOIN key again to toggle between on/off,
- RELEASE (CLEAR REQUEST) key - to deactivate the JOIN key and release the call on the active subunit.
- NIGHT SERVICE key - to activate/deactivate the blocking of the attendant console for new incoming calls. JOIN remains active
- TAPE RECORDING key - to activate/deactivate tape recording. JOIN remains active
- FUNCTIONAL 1 key - to activate/deactivate the call trace. JOIN remains active,
- HANDSET PLUG OFF for blocking the AC, JOIN will be deactivated
- All Voice Subunit key's (except that active - to execute JOIN)
- After JOIN and PA-Subunit key the attendant can select a park position (0-9) or exit the park menu by pressing the CHECK key.
All other keys will appear none functional to the user.