You might want to read this post for more examples, but to summarize:
WCF services can be exposed via a number of transports (e.g. Named Pipes, TCP, HTTP, MSMQ), encoded in a variety of ways (e.g. binary, binary-encoded-XML, XML, JSON). A transport and encoding combined together is known as a "binding". Standard bindings are documented here.
The amount of work you'll have to do to talk to this service depends on what binding the service provider has chosen (I couldn't tell since the URL you posted doesn't seem to be active).
If they've chosen something simple like basicHttpBinding, WebHttpBinding or even WSHttpBinding, then you should be able to create the necessary XML / JSON to interact with the service.
Note that since this appears to be an authentication service, the service provider may well be requiring that you support enhanced security infrastructures such as WS-Security, WS-Trust, etc.
However, if the service provider hasn't enabled metadata on their service (which would allow you to download a detailed description of the service's endpoints, bindings, message formats, etc.), and provides no documentation on their expected message formats etc., then you're going to have to do quite a lot of packet sniffing and guess-work to interact with their service.
You might also want to read some of these posts in order to understand how to access WCF services from mobile devices like Android:
http://fszlin.dymetis.com/post/2010/05/10/Comsuming-WCF-Services-With-Android.aspx
http://sochinda.wordpress.com/2012/01/18/communication-between-wcf-service-and-android-client/
http://shashidotnet.wordpress.com/2011/12/05/android-ax-app-part-1set-up-the-intermediate-wcf-service/
But, again, you'll have a MUCH easier time if you can get the service's metadata and/or documentation in order to understand the required transport-encoding bindings, message formats, security requirements, etc.
HTH.