Why would you think that? It's pretty trivial to do. You could try to obfuscate your traffic but that's just playing cat and mouse (and the ISP could just decide to start dropping anything that it doesn't recognize and seems to consume a significant amount of bandwidth).

I think the most efficient way to hide your service would be to tunnel it over HTTPS given that it's not really realistic to drop that when you're an ISP. Still, a relatively simple traffic analysis tool won't have too much difficulty differentiating between proper web browsing and something fishy over HTTPS even it it just looks at the shape of the traffic.