gistfile1.php

<?php
$apikey = "changeMe";
$salt = "changeMe";
$url = "http://local.mycallsystems.com/api/callsOnDemand?apikey=".urlencode($apikey)."&checksum=".urlencode(md5($apikey.$salt));
$start = time();
$request = 
[
  "time" => [
    "start" => [ 
	"Y"=> date('Y', $start)*1, 
	"M"=> date('m', $start)-1, 
	"D"=> date('d', $start)*1, 
	"h"=> date('H', $start)*1, 
	"m"=> date('i', $start)*1, 
	"s"=> date('s', $start)*1, 
	"z"=> date('Z', $start)/60
	],
  ],
  "numbers" => [
      "caller" => "+79179636377",
      "grouped_ids" => [ "1" => ["+79376674528"]],
      "callCenterNumber" => "+79036103234",
      "options" => [
        "redial" => 5,
        "interval" => 1
      ]
  ],
  "record" => [
    "on" => true
  ]
];
$data_string = json_encode($request);
$opts = array('http' =>
  array(
    'method'  => 'POST',
    'header'  => 
	  "Content-Type: application/json\r\n"
	. 'Content-Length: ' . strlen($data_string) . "\r\n",
    'content' => $data_string,
    'timeout' => 60,
    'ignore_errors' => true
  )
);
echo $url."\r\n";
print_r($request);

$context  = stream_context_create($opts);
$result = file_get_contents($url, false, $context, -1, 40000);
print_r($result);