International call progress tones for IP-PBX and VoIP telephony

Telephone Line Signalling

Ringing signal

  • The ringing signal drives the bell or ringer in a traditional telephone.
  • The ringing signal has the same cadence as the ringing tone.
  • Nominally 90 Vac, at 20 Hz (US) or 25 Hz (Europe).

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Related product: CPT-Master tone generator app