I looked at the Skype API docs (http://dev.skype.com/desktop-api-reference) and it seems to provide API functionality for interacting with a Skype program running on the same machine.
How can you send a chat message from a server that is not running Skype?
If you still need a solution for this problem, you can try now creating a Bot using Skype Bot Framework from Microsoft (https://docs.botframework.com/en-us/skype/getting-started).
It's kinda easy to implement, and the bot acts like a contact, wich must be added by someone to start interacting with your app behind it.
