some days ago I came across a problem during a project, i was trying to access Webservice from asp page that was hosted on another domain, but operation was "timed out". webservice was there you can call it you can review it, was working fine from DotNet. but when ever from asp/php it was not.
so after some research here is the remedy:
<add name="HttpGet" />
<add name="HttpPost" />
these line should be located in system.web tag of web.config.
according to Microsoft these lines are supposed to be already added to machine.config but in majority cases it is not.