SoapParam is a special low-level class for naming parameters and return ing values in non-WSDL mode. It is just a data holder and it does not have any special methods except the constructor. The constructor takes data to pass or return and name. It is possible to pass parameters directly as PHP values, but in this case it will be named as paramN and the SOAP Service may not understand them.
See also SoapClient::__call(), and SoapVar::SoapVar().