Unfortunately, there's not really enough information to help you. :-(
Please share your exact problem, and attach the code you are trying and any error messages you are receiving. Also post your config.xml file, index.html file (at least the HEAD portion so we can see your content-security-policy), and let us know what device(s) and platform(s) you are testing on.
In general, though, you'll use XMLHttpRequest (AJAX) to contact the web service. Make sure you whitelist the server and also add the server to your content-security-policy meta tag. But without knowing what code you are using, it's difficult to say more than that.
I am trying to call a Cross Domain WCF service from phonegap application. But there is some error ! How to do it ?
Not enough information. Refer to my prior post.