"trunk call" meaning in English

{
  "forms": [
    {
      "form": "trunk calls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "trunk call (plural trunk calls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "British English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Telephony",
          "orig": "en:Telephony",
          "parents": [
            "Electronics",
            "Telecommunications",
            "Technology",
            "Communication",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "a long-distance telephone call, especially one connected by the operator"
      ],
      "id": "en-trunk_call-en-noun-kLDEwOoq",
      "links": [
        [
          "telephony",
          "telephony"
        ],
        [
          "long-distance",
          "long-distance"
        ],
        [
          "telephone call",
          "telephone call"
        ],
        [
          "operator",
          "operator"
        ]
      ],
      "raw_glosses": [
        "(telephony, dated, chiefly British) a long-distance telephone call, especially one connected by the operator"
      ],
      "tags": [
        "British",
        "dated"
      ],
      "topics": [
        "communications",
        "electrical-engineering",
        "engineering",
        "natural-sciences",
        "physical-sciences",
        "telecommunications",
        "telephony"
      ]
    }
  ],
  "word": "trunk call"
}

{
  "forms": [
    {
      "form": "trunk calls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "trunk call (plural trunk calls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "British English",
        "English countable nouns",
        "English dated terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "en:Telephony"
      ],
      "glosses": [
        "a long-distance telephone call, especially one connected by the operator"
      ],
      "links": [
        [
          "telephony",
          "telephony"
        ],
        [
          "long-distance",
          "long-distance"
        ],
        [
          "telephone call",
          "telephone call"
        ],
        [
          "operator",
          "operator"
        ]
      ],
      "raw_glosses": [
        "(telephony, dated, chiefly British) a long-distance telephone call, especially one connected by the operator"
      ],
      "tags": [
        "British",
        "dated"
      ],
      "topics": [
        "communications",
        "electrical-engineering",
        "engineering",
        "natural-sciences",
        "physical-sciences",
        "telecommunications",
        "telephony"
      ]
    }
  ],
  "word": "trunk call"
}