ClientException in RequestException.php line 111:
Client error: `POST https://api.infobip.com/sms/1/text/single` resulted in a        `401 Unauthorized` response:
{"requestError":{"serviceException":   {"messageId":"UNAUTHORIZED","text":"Invalid login details"}}}

$data= '{
       "from":"InfoSMS",
       "to":"923227124444",
       "text":"Test SMS."
    }';
    $userstring = 'myuserame:password';
    $id =base64_encode ( 'myuserame:password' );
    echo 'Basic '.$id;
    $client = new GuzzleHttpClient();
    $request = $client->post('https://api.infobip.com/sms/1/text/single',array(
            'content-type' => 'application/json'
            ),['auth' =>  ['myusername', 'password']]);
    $request->setHeaders(array(
      'accept' => 'application/json',

      'authorization' => 'Basic '.$id,
      'content-type' => 'application/json'
    ));
    $request->setBody($data); #set body!
    $response = $request->send();
    echo $res->getStatusCode(); // 200
    echo $res->getBody();
    return $response;