I am on a Professional instance with API enabled. When I call a remote site using the Ajax Toolkit I am getting timeout errors for calls longer than 10 sec. I tried to set the timeout and the async params but it did not help to solve the problem.

 sforce.connection.remoteFunction({ 
                    url : endpoint_url, 
                    onSuccess : function(response) { callback_success(response);},
                    onFailure : function(response) { callback_failure(response);},  
                    method : "POST",
                    requestHeaders : {"Content-Type":"application/json", "charset":"utf-8"},
                    requestData : reqJSON,
                    timeout : 60000,
                    async : true
                });
any idea on how to extend the waiting time beyond the 10 sec?