{
  "opened": "2026-10",
  "sources": [
    {
      "kind": "Wikipedia",
      "title": "Interactive voice response",
      "url": "https://en.wikipedia.org/wiki/Interactive_voice_response"
    },
    {
      "kind": "Twilio",
      "title": "TwiML for Programmable Voice",
      "url": "https://www.twilio.com/docs/voice/twiml"
    },
    {
      "kind": "Twilio",
      "title": "Programmable Voice",
      "url": "https://www.twilio.com/docs/voice"
    },
    {
      "kind": "RFC",
      "title": "RFC 4733, RTP payload for DTMF",
      "url": "https://www.rfc-editor.org/rfc/rfc4733"
    },
    {
      "kind": "Vonage",
      "title": "Vonage Voice API",
      "url": "https://developer.vonage.com/en/voice/voice-api/overview"
    },
    {
      "kind": "Confirm",
      "title": "Vonage NCCO verb list. confirm. The Voice page names an NCCO reference. That reference was not opened.",
      "url": null
    },
    {
      "kind": "Confirm",
      "title": "A TwiML Pay price. confirm.",
      "url": null
    }
  ]
}