Tele-Communication (Telecom) Terms Glossary and Dictionary
Vacant Code Tone
Vacant Code Tone is used in crossbar systems to indicate that the dialed office code is unassigned. In step-by-step areas, this signal is called vacant level tone. For operator-originated calls, the verbal announcement is preceded by two flashes. In modern systems, recorded verbal announcements are used for this service. Vacant Code Tone is Low Tone for 0.5 seconds on, 0.5 seconds off, 0.5 seconds on and 1.5 seconds off.