If the SOAP protocol was not used to communicate with the XML Web service, such as HTTP-GET or HTTP-POST, the value of the WebService.SoapVersion property is System.Web.Services.Protocols.SoapProtocolVersion.Default.

For XML Web services that do not derive from the System.Web.Services.WebService class, the version of the SOAP protocol used to make the SOAP request to the XML Web service can be also be accessed using the "WebServiceSoapVersion" entry of the System.Web.HttpContext.Items property. That entry is of type System.Web.Services.Protocols.SoapProtocolVersion.