& is interpreted as amp;

[TheMatrixan]

By sending a clickmeeting query using http_build_query($params) without specifying additional parameters, their server could interprate & as amp;. To avoid that, the code should look like:
http_build_query( $params, '', '&' )

DevZone/API/examples/PHP/ClickMeetingRestClient.php

Line 124 in bed5389

curl_setopt($curl, CURLOPT_POSTFIELDS, $is_upload_file ? $params : http_build_query($params));