If you put in the wrong unlock code too many times, you've locked the
SIM. The reason it says "Contact Service Provider" is they're going to have to send you a new
SIM card when you explain to them what happened.
Now, we're talking about your new
SIM and not the old one, but if your unlock code is incorrect you might still have to contact the old service provider to get a new unlock code from them. It might be more feasible to buy the cheapest unlocked phone you can find in the country you're visiting.