Welcome to the RingCentral Community

You said you send a very small file and it works, that means that the code is working as expected. I doubt that you try to send some big file or unsupported content. So check out the MMS capabilities below.

RingCentral supported MMS content types

• Images: jpg/jpeg, png, gif, bmp, tif/tiff, svg
• Videos: 3gp, mp4, mpeg, flv, wmv, mov
• Audio: mp3
• Files: vcf/vcard, zip, rtf, html

Attachment size limit

The maximum size for MMS is carrier-dependent and normally around 1.2MB to 1.4MB.

You can send multiple attachments in a single MMS message. But the total size of attachments should not exceed the size limit above!

Also, if you want to see more from the error, change or print whatever from the exception you want to see within this block:

}catch (\RingCentral\SDK\Http\ApiException $e) {
  print 'Expected HTTP Error: ' . $e->getMessage() . PHP_EOL;
}

@Phong Vu

I am sending a jpg which is attached in the project (test.jpg). It has a size of 16.1 KB.

I know about the ability to get additional information from the Exception. But the $e does not contain anything except "code" - 400 and "message" - Bad Request

$e->apiResponse()->response()

Prints this object:

object(GuzzleHttp\Psr7\Response)#45 (6) {
  ["reasonPhrase":"GuzzleHttp\Psr7\Response":private]=>
  string(11) "Bad Request"
  ["statusCode":"GuzzleHttp\Psr7\Response":private]=>
  int(400)
  ["headers":"GuzzleHttp\Psr7\Response":private]=>
  array(4) {
    ["Server"]=>
    array(1) {
      [0]=>
      string(5) "nginx"
    }
    ["Date"]=>
    array(1) {
      [0]=>
      string(29) "Thu, 19 Dec 2019 16:45:36 GMT"
    }
    ["Content-Length"]=>
    array(1) {
      [0]=>
      string(1) "0"
    }
    ["Connection"]=>
    array(1) {
      [0]=>
      string(5) "close"
    }
  }
  ["headerNames":"GuzzleHttp\Psr7\Response":private]=>
  array(4) {
    ["server"]=>
    string(6) "Server"
    ["date"]=>
    string(4) "Date"
    ["content-length"]=>
    string(14) "Content-Length"
    ["connection"]=>
    string(10) "Connection"
  }
  ["protocol":"GuzzleHttp\Psr7\Response":private]=>
  string(3) "1.1"
  ["stream":"GuzzleHttp\Psr7\Response":private]=>
  object(GuzzleHttp\Psr7\Stream)#43 (7) {
    ["stream":"GuzzleHttp\Psr7\Stream":private]=>
    resource(75) of type (stream)
    ["size":"GuzzleHttp\Psr7\Stream":private]=>
    NULL
    ["seekable":"GuzzleHttp\Psr7\Stream":private]=>
    bool(true)
    ["readable":"GuzzleHttp\Psr7\Stream":private]=>
    bool(true)
    ["writable":"GuzzleHttp\Psr7\Stream":private]=>
    bool(true)
    ["uri":"GuzzleHttp\Psr7\Stream":private]=>
    string(10) "php://temp"
    ["customMetadata":"GuzzleHttp\Psr7\Stream":private]=>
    array(0) {
    }
  }
}