(PECL OAuth >= 0.99.1)
OAuth::getRequestToken — Fetch a request token
$request_token_url
   [, string $callback_url
  ] )Fetch a request token, secret and any additional response parameters from the service provider.
request_token_urlURL to the request token API.
callback_url
       OAuth callback URL. If callback_url is passed and is an empty value, it is set to "oob" to address the OAuth 2009.1 advisory.
      
   Returns an array containing the parsed OAuth response on success or FALSE on failure.
  
| Version | Description | 
|---|---|
| 1.0.0 | Previously returned NULLon failure, instead ofFALSE. | 
| 0.99.9 | The callback_urlparameter was added | 
Example #1 OAuth::getRequestToken() example
<?php
try {
    $oauth = new OAuth(OAUTH_CONSUMER_KEY,OAUTH_CONSUMER_SECRET);
    $request_token_info = $oauth->getRequestToken("https://example.com/oauth/request_token");
    if(!empty($request_token_info)) {
        print_r($request_token_info);
    } else {
        print "Failed fetching request token, response was: " . $oauth->getLastResponse();
    }
} catch(OAuthException $E) {
    echo "Response: ". $E->lastResponse . "\n";
}
?>
The above example will output something similar to:
Array
(
    [oauth_token] => some_token
    [oauth_token_secret] => some_token_secret
)