I’m currently working on a project where we want to integrate some of the Fedex functionality. I have the test account, and all the php code, and wsdl files. The one thing you can’t seem to find on their website, is the specific url for testing. I did some digging online and found a post from someone who ran into the same problem. The solution was to change the url from https://gateway.fedex.com:443/web-services to https://gatewaybeta.fedex.com:443/web-services
Fedex, please update your dev site with this little bit of information.