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cURL error when Integrating the PHP SDK on my project
Tags: sdk
Dec 11, 2015 at 7:22am   •   14 replies  •  0 likes


I am Using RingCentral Connect Platform PHP SDK ( to send fax messages, I get a curl error when i run the script. I have a developer account and testing the authenticate and Fax message and it works fine.

Error details:

Warning: curl_close(): 28 is not a valid cURL handle resource in <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\Client.php on line 104    Fatal error: Uncaught exception 'InvalidArgumentException' with message 'Invalid response string' in vendor\ringcentral\psr7\src\functions.php:478  Stack trace:  #0 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\ApiResponse.php(56): RingCentral\Psr7\parse_response('HTTP/1.1 0 OK??')  #1 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\Client.php(99): RingCentral\SDK\Http\ApiResponse->__construct(Object(RingCentral\Psr7\Request), false, 0)  #2 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\Client.php(25): RingCentral\SDK\Http\Client->loadResponse(Object(RingCentral\Psr7\Request))  #3 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Platform\Platform.php(214): RingCentral\SDK\Http\Client->send(Object(RingCentral\Psr7\Request))  #4 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Platform\Platform.php(301): RingCentral\SDK\Platform\Platform->sendReq in C:\inetpub\wwwroot\erexpress\public\vendor\ringcentral\ringcentral-php\src\Http\Client.php on line 44

Sample code (basically the sample code from -


use RingCentral\SDK\SDK;


$credentials = require(__DIR__ . '/vendor/ringcentral/ringcentral-php/demo/_credentials.php');

// Authorize

$platform->login($credentials['username'], $credentials['extension'], $credentials['password']);

// Find Fax-enabled phone number that belongs to extension

$phoneNumbers = $platform->get('/account/~/extension/~/phone-number', array('perPage' => 'max'))


print 'Fax Phone Number: ' . $credentials['username'] . PHP_EOL;

// Send Fax

$request = $rcsdk->createMultipartBuilder()


'to' => array(

array('phoneNumber' => $credentials['username']),


'faxResolution' => 'High',


->add('Plain Text', 'file.txt')

->add(fopen('', 'r'))


//print $request->getBody() . PHP_EOL;

$response = $platform->sendRequest($request);

print 'Sent Fax ' . $response->json()->uri . PHP_EOL;

14 Answers
answered on Dec 15, 2015 at 7:44am  
Hi Anil, 

We have resolved the issue we came across while trying to integrate Ringcentral PHP SDK. The issue was caused due to cURL SSL certificate issue.

Curl error: SSL certificate problem, verify that the CA cert is OK. Details: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed. Copied cacert.pem file and modified php.ini with the path to cacert.pem and it works.

Thank you for your support.

answered on Dec 30, 2015 at 4:22am  

Can we remove the header from the fax message :

"From: ER Express Fax Fax: (xxx) xxx xxxx     To:   Fax: +1(xxx) xxx-xxxx Page 1 of 1 12/30/2015"

answered on Dec 21, 2015 at 10:16pm  
Thank you Anil. That worked.

answered on Dec 21, 2015 at 6:00pm  
You could set the 'coverIndex' parameter as part of the body to 0 (none- no cover page ) for not displaying the cover page when you send a fax. 

Please take a look at our API Explorer to send Fax here :!/Messaging/v1_0_account__accountId__extension__extension...

answered on Dec 21, 2015 at 6:12am  

Do we have an option of not displaying the cover page either through the PHP SDK or through the Ringcentral outbound fax settings?

answered on Dec 17, 2015 at 1:39am  
Created a pdf file and as suggested included it as an attachment. Works as expected


answered on Dec 16, 2015 at 12:40pm  
You are trying to add HTML formatting to a plain text. You could try replacing the "<" and ">" symbols with "&lt" and "&gt" respectively but i suppose that would work with the text file. 

However, you could create a .pdf format file and you could have it included as your attachment before sending the fax.

answered on Dec 16, 2015 at 7:07am  

Can you tell me how i can format the fax message into a proper content with bold and next line

$request = $rcsdk->createMultipartBuilder()   
'to'  => array(
array('phoneNumber' => '12672800722'),
'faxResolution' => 'High',))
->add('Plain Text <Br> <b> Hello </b>', 'file.txt')
Right now the content shows up in the fax message as such:
Plain Text <Br> <b> Hello </b>.
Can we have html formatting:
Plain Text 

answered on Dec 15, 2015 at 12:17am  
Hi Anil,

I copied your code and tried to run it. 


Error 1
 -  Fatal error: Class 'RingCentral\SDK\SDK' not found in  C:\inetpub\wwwroot\ringcentral-php-demo\app\authenticate.php on line  10

The vendor\ringcentral\ringcentral-php folder was empty, so i downloaded the zip file from and pasted those files in the folder. The error disappears which leads to Error 2

Error 2 - 
Fatal error: Interface 'Psr\Http\Message\RequestInterface' not found in  C:\inetpub\wwwroot\ringcentral-php-demo\vendor\ringcentral\psr7\src\Request.php on line  13

answered on Dec 14, 2015 at 6:59pm  
I have created a sample Demo Application to Authenticate and send Fax . 

Please take a look at the file named " sendFax.php" in the Github Repo and you could modify the code accordingly within your application:

answered on Dec 14, 2015 at 6:28pm  
The sandbox username is +18024486632. I tested the sandbox credentials on ringway API explorer : Send Fax. It works fine and I receive a fax.

answered on Dec 14, 2015 at 10:31am  
Could you please provide the Organization Name or the sandbox number with which you are using the developer platform, we could take a look at your account. 

answered on Dec 14, 2015 at 2:46am  
Hi Anil,

Thank you for your response. I did instantiate the SDK Object. Somehow missed pasting it in  sample code above. 

I get the same error when i substituted the reference code you provided

Fatal error: Uncaught exception 'InvalidArgumentException' with message 'Invalid response string' in vendor\ringcentral\psr7\src\ functions.php:478
Stack trace:
#0 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\ ApiResponse.php(56): RingCentral\Psr7\parse_response('HTTP/1.1 0 OK??')
#1 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\ Client.php(99): RingCentral\SDK\Http\ApiResponse->__construct(Object(RingCentral\Psr7\Request), false, 0)
#2 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Http\ Client.php(25): RingCentral\SDK\Http\Client->loadResponse(Object(RingCentral\Psr7\Request))
#3 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Platform\ Platform.php(214): RingCentral\SDK\Http\Client->send(Object(RingCentral\Psr7\Request))
#4 <path_to_project>\vendor\ringcentral\ringcentral-php\src\Platform\ Platform.php(301): RingCentral\SDK\Platform\Platform->sendReq in C:\inetpub\wwwroot\erexpress\public\vendor\ringcentral\ringcentral-php\src\Http\ Client.php on line 44
This error occurs when i try to call the  

// Authorize call
        $platform->login($credentials['username'], $credentials['extension'], $credentials['password'], true);

answered on Dec 11, 2015 at 11:00am  
Hi ,

Did you instantiate the SDK Object within the sample code that your are using to Authenticate and Send Fax :

Please include this code within your demo application :

// Create SDK instance
$rcsdk = new SDK($credentials['appKey'], $credentials['appSecret'], $credentials['server'], 'Demo', '1.0.0');
$platform = $rcsdk->platform();
If you take a lookat our Demo Folder within the SDK you would see a file named "_credentialsSample.json" . Please make sure you are using all the details on your sandbox account like appKey, appSecret and the credentials on your sandbox account etc. 

Also for your reference, i am providing a sample code below to Authenticate and Send Fax : 

$credentials_file = count($argv) > 1         ? $argv[1] : __DIR__ . '/_credentialsSample.json';

        $credentials = json_decode(file_get_contents($credentials_file), true);

        // Create SDK instance
        $rcsdk = new SDK($credentials['appKey'], $credentials['appSecret'], $credentials['server'], 'Demo', '1.0.0');
        $platform = $rcsdk->platform();
        // // Authorize
        $platform->login($credentials['username'], $credentials['extension'], $credentials['password'], true);
        $request = $rcsdk->createMultipartBuilder()
                     'to'         => array(
                         array('phoneNumber' => 'toNumber'),
                     'faxResolution' => 'High',
                 ->add('Plain Text', 'file.txt')
                 ->add(fopen('', 'r'))    

        $response = $platform->sendRequest($request);
        print_r($response->request()-> getHeaders());


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