Tele-Communication (Telecom) Terms Glossary and Dictionary
Special Dial Tone
Special Dial Tone is used with Three-Way Calling, Centrex station dial transfer, and Centrex conference (station or attendant) services. The user on an existing connection flashes the switch-hook, receives special dial tone, and dials number of the third party to be added to the connection. Special Dial Tone is 350 Hz and 440 Hz at -13 dBm0/frequency for 0.1 second on, 0.1 second off, 0.1 second on, 0.1 second off, 0.1 second on, 0.1 second off, and then on steady.