Android does not support SOAP library. You can either write your own, or use something like kSOAP 2. Some people have been able to compile and use kSOAP2 in their own projects.
SOAP is an ill-suited technology for use on Android (or mobile devices in general) because of the processing/parsing overhead that’s required. A REST services is a lighter weight solution and that’s what I would suggest. Android comes with a SAX parser, and it’s fairly trivial to use. If you are absolutely required to handle/parse SOAP on a mobile device then I feel sorry for you, the best advice I can offer is just not to use SOAP.