The SOAPAction path value can be found from the script you sending the request by adding to it ?wsdl. In my case it https://aisws.ingos.ru/sales-test/SalesService.svc?wsdl.
Note, that you will not see it just by opening in browser, because it returns content-type xml. To read it you should use cUrl or anything else.
CLICK HERE to find out more related problems solutions.