VIES SOAP gives error SERVICE_UNAVAILABLE

I found the answer. In fact the WSDL was not the correct one... TT The correct one is http://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl

Ran into the same problem.

For using the test service http://ec.europa.eu/taxation_customs/vies/services/checkVatTestService

you have to use one of the following numbers as VAT (not an actual VAT):

100 = Valid request with Valid VAT Number
200 = Valid request with an Invalid VAT Number
201 = Error : INVALID_INPUT
202 = Error : INVALID_REQUESTER_INFO
300 = Error : SERVICE_UNAVAILABLE
301 = Error : MS_UNAVAILABLE
302 = Error : TIMEOUT
400 = Error : VAT_BLOCKED
401 = Error : IP_BLOCKED
500 = Error : GLOBAL_MAX_CONCURRENT_REQ
501 = Error : GLOBAL_MAX_CONCURRENT_REQ_TIME
600 = Error : MS_MAX_CONCURRENT_REQ
601 = Error : MS_MAX_CONCURRENT_REQ_TIME

Example for request that returns "valid VAT number":

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:ec.europa.eu:taxud:vies:services:checkVat:types">
   <soapenv:Header/>
   <soapenv:Body>
      <urn:checkVat>
         <urn:countryCode>DE</urn:countryCode>
         <urn:vatNumber>100</urn:vatNumber>
      </urn:checkVat>
   </soapenv:Body>
</soapenv:Envelope>