In the game, if you do things 4 times correctly, you should win. (i think)

If you're stuck:

• Crazy caller is either unsure or just talks nonsense. Ignore him. To do so, select valve and pick 3rd option.
• Terrorist says only the opposite of what to do. Ask him what to NOT do and do that.
• Sapper says only useful information.

To distinguish them, follow this:

1. If caller is unsure, its crazy one. starts with (I think I know)
2. Ask what not to do.
3. If some unrelated stuff is told, its crazy one. like (acoustics, sneeze and don't look)
4. If caller starts with "DONT do something" when asked what not to do, then its a sapper. Trust him.
5. Else it's likely a terrorist. Follow his DONTs.

It's about 80% correct strategy. You'll win eventually.