Call webservice through JavaScript

I am calling websevice through javascript by using SOAPClient and its working in Internet Explorer But not working in Firefox.

Actually Its working in firefox also when a webservice within same folder or same project.

But it not working in firefox if the webservice is not within same project.

For Internet Explorer it works in both the cases.

May be Cross-site HTTP requests issue?

i've also found that if you're using a .net webservice and it's running on the test/debug server instead of the real iis server, explorer's xmlhttprequest will accept answers, but firefox and safari's won't. (does the port count in the cross-site issue??)