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Curl to PHP: https://incarnate.github.io/curl-to-php/

Update: I find that  it doesn't support '-F' at all, so ignore this one.

Drew,

Try out my PHP "Lite" SDK. It's a 1-file, 0-dependency library designed to support older PHP and uses cURL.

You can see a fax example using the SDK here:

https://github.com/grokify/ringcentral-sdk-php-lite#send-a-fax

You can see the SDK's cURL code here:

https://github.com/grokify/ringcentral-sdk-php-lite/blob/master/src/ringcentrallite.php#L139

I don't have PHP 5.2.3, so let me know if it works for you.

But how do I translate that to PHP cURL lib?... such as using curl_init(), curl-setopt(), etc?

Ya, 1.5 days were stuck reading docs and the other 1.5 days were trying to implement things fruitlessly. 

Been stuck for the past 3 days.

You should have asked for help earlier :)

I can show you how to do it with curl. You try to adjust it for PHP curl. 

curl \
--header "Accept: application/json" \
--header "Authorization: Bearer <token>" \
-F "request=@request.json;type=application/json" \
-F " attachment=@hello.txt;type=text/plain" \
" https://platform.devtest.ringcentral.com/restapi/v1.0/account/~/extension/~/fax";


Content of request.json file:
{
"to": [{ "phoneNumber": <fax receiver> }]
}


Content of hello.txt:
<Whatever text you want to send.>


You can also send pdf:
-F " attachment=@test.pdf;type=application/pdf"