"dial tone" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Compositions en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Lexique en anglais des télécommunications",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Locutions nominales en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "Composé de dial et de tone."
  ],
  "forms": [
    {
      "form": "dial tones",
      "tags": [
        "plural"
      ]
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Locution nominale",
  "related": [
    {
      "word": "busy signal"
    },
    {
      "sense": "tonalité d'occupation",
      "word": "busy tone"
    }
  ],
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Lexique en anglais de la téléphonie",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Anglais des États-Unis",
          "orig": "anglais des États-Unis",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Tonalité d’invitation à numéroter (au téléphone)."
      ],
      "id": "fr-dial_tone-en-noun-3vRUZAIh",
      "raw_tags": [
        "États-Unis"
      ],
      "topics": [
        "telephony"
      ]
    }
  ],
  "synonyms": [
    {
      "raw_tags": [
        "Royaume-Uni"
      ],
      "word": "dialling tone"
    }
  ],
  "word": "dial tone"
}

{
  "categories": [
    "Compositions en anglais",
    "Lexique en anglais des télécommunications",
    "Locutions nominales en anglais",
    "anglais"
  ],
  "etymology_texts": [
    "Composé de dial et de tone."
  ],
  "forms": [
    {
      "form": "dial tones",
      "tags": [
        "plural"
      ]
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Locution nominale",
  "related": [
    {
      "word": "busy signal"
    },
    {
      "sense": "tonalité d'occupation",
      "word": "busy tone"
    }
  ],
  "senses": [
    {
      "categories": [
        "Lexique en anglais de la téléphonie",
        "anglais des États-Unis"
      ],
      "glosses": [
        "Tonalité d’invitation à numéroter (au téléphone)."
      ],
      "raw_tags": [
        "États-Unis"
      ],
      "topics": [
        "telephony"
      ]
    }
  ],
  "synonyms": [
    {
      "raw_tags": [
        "Royaume-Uni"
      ],
      "word": "dialling tone"
    }
  ],
  "word": "dial tone"
}