You do NOT need a provisional in order to get a Utility patent. You can bypass the provisional altogether if you are ready to file a full utility patent. My impression is that provisionals in themselves do not prevent you from getting an international patent. What DOES make you ineligible for an international patent is if you try to sell your product or you disclose your product in public BEFORE you file the international application. In the US, you have 1 year to file the application after an offer for sale or public disclosure. But in other countries, all patents have to be filed BEFORE you do any of that. So, if you get a provisional patent and then put up a website, go to a tradeshow or try to sell your invention on eBay, you forfeit your rights to ever being able to get an international patent. If you do all those things but then don’t file a US application within 12 months, you will never be granted a patent anywhere in the world.