Absolutely not. Once your schedule is published you have no responsibility to the company except letting them know where they can reach you. But you don't need to answer the phone. If you answer the phone, then they can change your schedule as long as it is legal. If you don't answer, then they move on to the next option, which is probably the origianl that was scheduled for the flight but will now be going into overtime....
When you are in the hotel YOU HAVE NO RESPONSIBILITY TO ANSWER THE PHONE!! You can drink as much as you want as long as it is legal and safe in reference to your scheduled departure time. If they reach you and would like you to operate earlier, then it is a request in their part which is subject to you not having drunk in the last 12 hours and also you accepting that you are well rested.
If they delay you on your long-haul overnight, make sure you do your math. If the delay is 4 hours or greater, then it will start eating into your FDP. Less than four hours, then your FDP remains the same. You need to do the math if they delay you more than 4 hours because it might be the determining factor on wether you will get a fourth guy, or wether you will time out and get delayed another 10.
In all cases, it is very important that the flight is not scheduled to operate with discretion. THAT IS ILLEGAL AND YOU ARE PUTTING YOUR LISCENSE IN JEOPARDY. They can't schedule you to use discretion. If they ask you, then please ask them if it is legal to do what they want you to do. If they say it is legal, then it probably is. If you still believe it is not, then get more heads to look at the situation. Ask to speak to the duty manager and even call the fleet office. Whatever, CYA is the name of the game.
