Generate XML from Model Object

private string CreateXMLModalPhone(Demographics objDemographics)
        {
            String XmlString;
            XmlDocument objdoc = new XmlDocument();

            // declare your XML
            XmlNode declaration = objdoc .CreateNode(XmlNodeType.XmlDeclaration, null, null);
            objdoc.AppendChild(declaration);

            // Root element: RequestItemStatus
            XmlElement root = objdoc.CreateElement("Phone");
            objdoc.AppendChild(root);

            for (Int32 i = 0; i < objDemographics.PhoneType.Length; i++)
            {

                //your Main element: RequestItem
                XmlElement RequestItem = objdoc.CreateElement("PhoneNoDetails");
                root.AppendChild(RequestItem);

                //your Sub-element: RequestItemId
                XmlElement RequestItemId = objdoc.CreateElement("PhoneTypeId");
                RequestItemId.InnerText = objDemographics.PhoneType[i].ToString();
                RequestItem.AppendChild(RequestItemId);

                //your Sub-element: comments
                XmlElement comments = objdoc.CreateElement("PhoneNo");
                comments.InnerText = objDemographics.PhoneNo[i].ToString();
                RequestItem.AppendChild(comments);

            }

            XmlString = objdoc.InnerXml;

            return XmlString.ToString();
        }