I solved my problem with the help from Ron Beyer
public interface IWCFRestService
{
[OperationContract]
[WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Xml, BodyStyle = WebMessageBodyStyle.Wrapped,
UriTemplate = "/JSONData/{id}")]
string JSONData(string id);
}
It must be GET instead of POST.
SO its working fine and service has invoked.