<!-- Global PSTN supervisory tones -->
<!ELEMENT global-tones (tone-set)* >
<!ELEMENT tone-set (dial-tone
                   |ringing-tone
                   |busy-tone
                   |congestion-tone
                   |number-unobtainable-tone
                   |special-information-tone
                   |call-waiting-tone
                   |waiting-tone
                   |pay-tone
                   |payphone-recognition-tone
                   |warning-tone
                   |test-number-tone
                   |end-of-three-party-service-tone
                   |service-activated-tone
                   |record-tone
                   |facilities-tone
                   |offering-tone
                   |route-tone
                   |confirmation-tone
                   |intrusion-tone
                   |intercept-tone
                   |reorder-tone
                   |holding-tone
                   |search-tone
                   |acceptance-tone
                   |executive-override-tone
                   |function-acknowledge-tone
                   |queue-tone
                   |valid-tone-radio-paging
                   |notify-tone
                   |preemption-tone
                   |comfort-tone
                   |connection-tone
                   |refusal-tone
                   |line-lockout-tone
                   |permanent-signal-tone
                   |identification-tone
                   |positive-indication-tone
                   |negative-indication-tone)* >
<!ATTLIST tone-set
  country   CDATA   #REQUIRED
  uncode    CDATA   #REQUIRED
  >

<!-- Dialing tones -->
<!ELEMENT dial-tone (step)* >
<!ATTLIST dial-tone
  domain    CDATA   #IMPLIED
  type      CDATA   #IMPLIED
  >

<!-- Post-dialing tones -->
<!ELEMENT ringing-tone (step)* >
<!ATTLIST ringing-tone
  domain    CDATA   #IMPLIED
  type      CDATA   #IMPLIED
  >

<!-- Dial result tones -->
<!ELEMENT busy-tone (step)* >
<!ATTLIST busy-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT congestion-tone (step)* >
<!ATTLIST congestion-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT number-unobtainable-tone (step)* >
<!ATTLIST number-unobtainable-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT special-information-tone (step)* >
<!ATTLIST special-information-tone
  domain    CDATA   #IMPLIED
  >

<!ELEMENT call-waiting-tone (step)* >
<!ATTLIST call-waiting-tone
  domain    CDATA   #IMPLIED
  type      CDATA   #IMPLIED
  >

<!-- Payment related tones -->
<!ELEMENT pay-tone (step)* >
<!ATTLIST pay-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT payphone-recognition-tone (step)* >
<!ATTLIST payphone-recognition-tone
  domain    CDATA   #IMPLIED
  >

<!ELEMENT warning-tone (step)* >
<!ATTLIST warning-tone
  type      CDATA   #IMPLIED
  domain    CDATA   #IMPLIED
  >
<!ELEMENT reorder-tone (step)* >
<!ATTLIST reorder-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT waiting-tone (step)* >
<!ATTLIST waiting-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT test-number-tone (step)* >
<!ATTLIST test-number-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT end-of-three-party-service-tone (step)* >
<!ATTLIST end-of-three-party-service-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT service-activated-tone (step)* >
<!ATTLIST service-activated-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT record-tone (step)* >
<!ATTLIST record-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT facilities-tone (step)* >
<!ATTLIST facilities-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT offering-tone (step)* >
<!ATTLIST offering-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT route-tone (step)* >
<!ATTLIST route-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT confirmation-tone (step)* >
<!ATTLIST confirmation-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT intrusion-tone (step)* >
<!ATTLIST intrusion-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT intercept-tone (step)* >
<!ATTLIST intercept-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT holding-tone (step)* >
<!ATTLIST holding-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT search-tone (step)* >
<!ATTLIST search-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT acceptance-tone (step)* >
<!ATTLIST acceptance-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT executive-override-tone (step)* >
<!ATTLIST executive-override-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT function-acknowledge-tone (step)* >
<!ATTLIST function-acknowledge-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT queue-tone (step)* >
<!ATTLIST queue-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT valid-tone-radio-paging (step)* >
<!ATTLIST valid-tone-radio-paging
  domain    CDATA   #IMPLIED
  >
<!ELEMENT notify-tone (step)* >
<!ATTLIST notify-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT preemption-tone (step)* >
<!ATTLIST preemption-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT comfort-tone (step)* >
<!ATTLIST comfort-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT connection-tone (step)* >
<!ATTLIST connection-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT refusal-tone (step)* >
<!ATTLIST refusal-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT line-lockout-tone (step)* >
<!ATTLIST line-lockout-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT permanent-signal-tone (step)* >
<!ATTLIST permanent-signal-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT identification-tone (step)* >
<!ATTLIST identification-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT positive-indication-tone (step)* >
<!ATTLIST positive-indication-tone
  domain    CDATA   #IMPLIED
  >
<!ELEMENT negative-indication-tone (step)* >
<!ATTLIST negative-indication-tone
  domain    CDATA   #IMPLIED
  >

<!ELEMENT step (step|EMPTY)* >
<!ATTLIST step
  cycles                CDATA   #IMPLIED
  freq                  CDATA   #IMPLIED
  level                 CDATA   #IMPLIED
  length                CDATA   #IMPLIED
  recorded-announcement CDATA   #IMPLIED
  recognition-length    CDATA   #IMPLIED
  >