http://www.service-repository.com/
Copy the "Message Structure" (under Interface, Operations, Input) or "XML" (under the "Call it!" operation).
URL is the location for the service under Endpoints.

SoapUI app graphically generates SOAP envelopes.
http://sourceforge.net/projects/soapui/files/latest/download
http://www.soapui.org/getting-started/your-first-soapui-project.html

Fetch WSDL:
curl -O http://ws.cdyne.com/ip2geo/ip2geo.asmx'?wsdl'
The SOAP Action requird for v 1.1. header is specified in there.

V 1.1:
curl -o ip2go-response1.1.xml -H 'Content-Type: text/xml; charset=utf-8' -H SOAPAction:http://ws.cdyne.com/ResolveIP -d@ip2go-request1.1.xml http://ws.cdyne.com/ip2geo/ip2geo.asmx

V 1.2:
curl -o ip2go-response1.2.xml -H 'Content-Type: application/soap+xml; charset=utf-8' -d@ip2go-request1.2.xml http://ws.cdyne.com/ip2geo/ip2geo.asmx



Examples from http://stackoverflow.com/questions/8167210/how-to-test-web-service-using-command-line-curl :
curl -X GET --basic --user username:password \
     https://www.example.com/mobile/resource

curl -X DELETE --basic --user username:password \
     https://www.example.com/mobile/resource

curl -X PUT --basic --user username:password -d 'param1_name=param1_value' \
     -d 'param2_name=param2_value' https://www.example.com/mobile/resource
POSTing a file and additional parameter

curl -X POST -F 'param_name=@/filepath/filename' \
     -F 'extra_param_name=extra_param_value' --basic --user username:password \
     https://www.example.com/mobile/resource
+ REST:
$ curl https://api.twitter.com/1/help/configuration.xml  | xmllint --format -
$ curl https://api.twitter.com/1/help/configuration.json | python -mjson.tool
Tested on Ubuntu 11.0.4/11.10.

Another issue is the desired content type. Twitter uses .xml/.json extension, but more idiomatic REST would require Accept header:

$ curl -H "Accept: application/json"