This is how odoo field get the current  model

https://github.com/odoo/odoo/blob/849ece86a6cf49c0a9249ed910aa52add197f431/addons/web/static/src/views/fields/binary/binary_field.js#L43

It seem that you trying to create a new field extend from some field right, i don't think what you are coding seem fit to odoo in general, window.makeCall is not the way to define some method in Odoo OWL or Legacy

window.makeCall = function(event) {
    event.preventDefault();

    var $button = $(event.currentTarget);
    var modelName = this.dataset.model;
    var recordId = $button.attr('data-record-id');
    var phone = $button.prev('input.o_input').val();

    console.log('Model Name:', modelName);
    // Determine context and set data accordingly
    var data = {
        phone: phone,
        contact_id: modelName === 'res.partner' ? recordId : undefined,
        lead_id: modelName === 'crm.lead' ? recordId : undefined,
    };

    // Example of fetching additional data if needed
    if (modelName === 'crm.lead') {
        odoo.define('model.func', function(require) {
            var rpc = require('web.rpc');
            rpc.query({
                model: modelName,
                method: 'read',
                args: [[recordId], ['partner_id']],
            }).then(function(records) {
                var record = records[0];
                if (record.partner_id) {
                    data.contact_id = record.partner_id[0];
                }

                // Now, make the AJAX call with the complete data object
                $.ajax({
                    url: url,
                    type: "POST",
                    contentType: "application/json",
                    data: JSON.stringify(data),
                    success: function(response) {
                        console.log("Call initiated successfully", response);
                    },
                    error: function(error) {
                        console.error("Error initiating call", error);
                    }
                });
            });
        });
    } else {
        // If not crm.lead or additional data not needed, make the call directly
        $.ajax({
            url: url,
            type: "POST",
            contentType: "application/json",
            data: JSON.stringify(data),
            success: function(response) {
                console.log("Call initiated successfully", response);
            },
            error: function(error) {
                console.error("Error initiating call", error);
            }
        });
    }
};