Here are the HTTP status codes that webservices can return
The billing server is probably down. Please contact administrator.error null
If you call using HTTP, your request will be automatically redirected to HTTPS.
The parameters have to be URL encoded.
Only GET is allowed. OPTION and HEAD are also accepted, but POST is not.
Same-origin_policy : some browsers or software doesn't allow you to make Ajax calls to a different server than the current page one. If you have some problems, use a kind of proxy on you server, that will make calls and send them back to the browser.
We have some CORS or Cross-origin_resource_sharing but can not give warranty on that.