In recent years phone companies have made international service much more simple and affordable.
To stay in touch with loved ones back home, it's usually easy to make free internet-based calls via complimentary WiFi in hotels and other hotspots. Skype, WhatsApp, and iPhone's Facetime are great options for messaging and calls.
If you have a need to text to numbers outside your carrier or call landlines in the USA, you can purchase a temporary International calling plan from your phone service provider.
It can be worthwhile to purchase a temporary International data plan for those times when you're without WiFi and need to get online. Lost and need to pull up directions? Have an important email you're waiting for or need to respond to? Want to post to Instagram or Facebook while at a site? You'll need data for that. And you'll probably need more than you expect.
Keep in mind that using WiFi does not count against the data you've purchased. But, frankly, WiFi can be spotty and unpredictable.
Always consult your phone carrier if you intend to use your phone overseas, and discuss with an actual agent via phone or chat what options will work best for you. Ask lots of questions to determine whether there will be hidden or unexpected charges.
Be sure you understand clearly when/where to turn off Data Roaming so that you don't encounter exorbitant unexpected charges.
And don't forget to bring your charger and suitable adapter(s).
With a little forethought, international phone usage can be easy and painless. Don't skimp here. While you don't want to spend your holiday online, the truth is that we use our phones for everything. It's better to pay for more than you think you'll need than to come up short on your data plan and have to pay expensive overage fees or to contact your carrier mid-trip to expand your plan.
Plan ahead, and then relax and enjoy your travels.