This is fairly easy to do, basically you set up an API server, and then you interact with them, and they interact with you, through that server.
I guess the regular API server example is a good starting place.
\Clarion10\Examples\NetTalk\Web Server\WebServiceRequiresXFiles (77)
In NetTalk 10 I have a similar setup with the Twilio API, so I guess that will make a tighter example, but that'll only be available once NT 10 ships.
cheers
Bruce