"call upon" meaning in English

{
  "forms": [
    {
      "form": "calls upon",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "calling upon",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "called upon",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "called upon",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "call upon (third-person singular simple present calls upon, present participle calling upon, simple past and past participle called upon)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "certain senses",
          "word": "call on"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English phrasal verbs with particle (upon)",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1959 March, “The 2,500 h.p. electric locomotives for the Kent Coast electrification”, in Trains Illustrated, page 123",
          "text": "They will be called upon to deal with freight trains of up to 900 tons over gradients considerably steeper than those of the Central Section—for example, the frequent stretches of 1 in 100 between Victoria and the Medway towns—and their running to fast schedules will include the haulage of the \"Night Ferry\", which may load up to as much as 700 tons, and fully-fitted trains of 30 or more heavy Continental train ferry wagons.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative form of call on (certain senses)."
      ],
      "id": "en-call_upon-en-verb-InELBgyO",
      "links": [
        [
          "call on",
          "call on#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "call upon"
}

{
  "forms": [
    {
      "form": "calls upon",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "calling upon",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "called upon",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "called upon",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "call upon (third-person singular simple present calls upon, present participle calling upon, simple past and past participle called upon)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "certain senses",
          "word": "call on"
        }
      ],
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English phrasal verbs",
        "English phrasal verbs with particle (upon)",
        "English terms with quotations",
        "English verbs"
      ],
      "examples": [
        {
          "ref": "1959 March, “The 2,500 h.p. electric locomotives for the Kent Coast electrification”, in Trains Illustrated, page 123",
          "text": "They will be called upon to deal with freight trains of up to 900 tons over gradients considerably steeper than those of the Central Section—for example, the frequent stretches of 1 in 100 between Victoria and the Medway towns—and their running to fast schedules will include the haulage of the \"Night Ferry\", which may load up to as much as 700 tons, and fully-fitted trains of 30 or more heavy Continental train ferry wagons.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative form of call on (certain senses)."
      ],
      "links": [
        [
          "call on",
          "call on#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "call upon"
}