Assuming you are using UCCX or IPIVR and not UCCE or CVP: You can use the HTTP steps if you are on Premium licensing to retrieve an XML document from another server. That server can provide any interface you want as long as it saves it into a properly formatted XML document for CCX to retrieve.

You could use an XML file in the document repository if you are on Standard or Enhanced but this requires you to give the contact center personnel admin role on CCX Administration and they must upload the XML file directly.

The script can use xPath to parse the XML file and get the data it needs into a variable it can act upon.

Oh, if you have Premium licensing you could do an ODBC connection to a supported SQL database to get this information as well.