If this is an internal service and you are calling from .NET to .NET then using a SOAP based Web Service may very well be the easiest solution. If it's a public facing solution it's probably better - as Craig has mentioned - to use a REST based API using ASP.NET Web API. While REST based services are more appropriate today, consuming them can be a bit more work as there's no service definition and you manually need to create the types that can receive the client data. With SOAP you can just point at the service and get a proxy generated for you - so it can be somewhat easier to work with.
If you go the REST route you can use Web API on the server, and a standard HTTP client (like HttpClient()) that can automatically deserialize JSON into objects that you create on your own.
+++ Rick ---
>Hi,
>
>I need to understand (and learn) a .NET technology that would be used as follows:
>
>Some 3P software has to add record(s) to a table in SQL Server database. Then my application will "deal" with this record(s) (this is not relevant to the question). I may need to "tell" the 3P software how the data from their program will go to the database. Will I need to build Web Services to consume their data/messages? (not sure if "consume" is the right term though). Or another technology?
>
>What technology should I look at and learn?
>
>TIA