{
  "id": "t13-l01-three-ways-a-call-can-enter",
  "title": "Three ways a call can enter",
  "checked": "2026-10",
  "sources": [
    {
      "label": "Technical requirements PDF",
      "url": "https://documentation-be.five9.com/bundle/five9-technical-requirements/raw/resource/enus/five9-technical-requirements.pdf",
      "kind": "vendor",
      "status": "ok",
      "lastChecked": "2026-10",
      "note": "Fetched for this lab in October 2026. Re-read before you buy hardware or open a firewall."
    },
    {
      "label": "SIP trunk options chapter",
      "url": "https://documentation.five9.com/bundle/technical-reqs/page/technical-reqs/SIP-trunk-options/_ch-five9-sip-trunk-options.htm",
      "kind": "vendor",
      "status": "ok",
      "lastChecked": "2026-10"
    },
    {
      "label": "RFC 3261",
      "url": "https://www.rfc-editor.org/rfc/rfc3261",
      "kind": "rfc",
      "status": "ok",
      "lastChecked": "2026-10"
    },
    {
      "label": "RFC 3550, RTP",
      "url": "https://www.rfc-editor.org/rfc/rfc3550",
      "kind": "rfc",
      "status": "ok",
      "lastChecked": "2026-10"
    },
    {
      "label": "RFC 3551, RTP profile for audio and video",
      "url": "https://www.rfc-editor.org/rfc/rfc3551",
      "kind": "rfc",
      "status": "ok",
      "lastChecked": "2026-10"
    },
    {
      "label": "ITU-T G.711",
      "url": "https://www.itu.int/rec/T-REC-G.711",
      "kind": "standard",
      "status": "ok",
      "lastChecked": "2026-10"
    },
    {
      "label": "ITU-T E.164, international public telecommunication numbering",
      "url": "https://www.itu.int/rec/T-REC-E.164",
      "kind": "standard",
      "status": "ok",
      "lastChecked": "2026-10"
    }
  ]
}