From: John Thorne <[email protected]> Subject: GB Dial tones
Ray, GB Dial tones... 1. GB dial tones are 350Hz + 440Hz simultaneously (+/-5% tolerance) at between -27dB and 0dB power level (each tone 3dB down). 2. Special dial tone may be applied when supplementary services are enabled. This is the same as above but 350Hz or both frequencies are cadanced at 750ms on, 750ms off (+/- 25%) 3. Carrier dial tone is applied when connection is made to a non-BT carrier such as Mercury. This is a single tone of 1111Hz (+/-20%) at the same power levels as above. 4. "Old" BT dial tone is now extemely rare and was either 30 or 50Hz (very) rich in harmonics having the same power level as above. Ref. BS6305:1992 and ETSI 300 001 Rev 3 Hope this helps John Thorne
