Here is API code for SMS provider site and I want use PHP data variables inside of places that should be fill with changeable variables I tried some solutions but no SMS received after test that

  $curl = curl_init();

  curl_setopt_array($curl, array(
    CURLOPT_URL => 'https://api......',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_ENCODING => '',
    CURLOPT_MAXREDIRS => 10,
    CURLOPT_TIMEOUT => 0,
    CURLOPT_FOLLOWLOCATION => true,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_POSTFIELDS =>'{
    "mobile": "xxxx",   ----> i want use php variables like $number  here
    "templateId": xxxx,     ------>  and here 
    "parameters": [
      {
        "name": "NAME",
        "value": "xxx"    ---------> here
      },
      {
          "name":"DESCRIPTION",
          "value":"xxx"         ------------> here
      },
      {
          "name":"ORDER",
          "value":"xxx"        -----> here
          
      }
    ]
  }',
    CURLOPT_HTTPHEADER => array(
      'Content-Type: application/json',
      'Accept: text/plain',
      'x-api-key:xxxxxxxx...'
    ),
  ));

  $response = curl_exec($curl);

  curl_close($curl);
 echo $response;