The cheapest reliable way to use your cell phone while traveling internationally is to buy a local SIM card at your destination and pop it into your phone. Done.
Having said that, if you’re traveling for pleasure, I would strongly encourage you to simply put your phone in airplane mode and leave it that way for the entirety of your trip. If you really need to contact someone to let them know you arrived safely, you can use the free wifi that most hotels provide to either shoot out a quick email, send an iMessage (if both you and the recipient are iPhone users), or make a voice call using an app like Telegram.
Other than that, an international vacation is the perfect opportunity to unplug from the world and enjoy your local surroundings. I assure you: none of us are really that important, and if you’re unreachable for a couple of weeks, the Earth will keep spinning.
Many of you will scoff at this idea and find the concept terrifying. Understandable; over the last several years, so many of us have evolved into cell phone addicts who can no longer function properly without being constantly connected.
But at least consider the idea of untethering yourself for a short amount of time. It’s one less thing to worry about when you travel, and I find it quite liberating to know that no one can contact me while I’m enjoying my leisure time exploring a new locale.