�1���� General
�2����
Electrical levels for tones
�3����
Acoustical levels for tones
�4����
Dial tone
�5����
Ringing tone
�6����
Busy tone and congestion tone
�7����
Special information tone
�8���
�Warning tone to indicate that a
conversation is being recorded
�9����
Payphone recognition tone
������� 9.3���� Duration and level
10���� Call waiting tone
11���� Caller waiting tone
12���� Machine recognition of tones
Annex A� Digital generation of tones
Annex B� Examples for limitation of
spurious components of the dial tone with respect to interference with the
frequencies recommended for pushbutton telephone sets in Recommendation Q.23
������� B.1���� Method A (used by ATT)
������� B.2���� Method B (used by the Federal Republic of Germany)