I used to be one of those people who had a little pocket full of different SIM cards. I would pick up new cards whenever I would switch locations: Canada, USA, France, Switzerland, UK. And being slightly disorganized, I would sometimes lose them.. they're so small and slippery!
Luckily I don't have to worry about that anymore. I now have service in pretty much every country I go to, without having to change SIM cards; actually I don't even have a SIM card. How did I achieve this?
Project Fi by Google
First off, this post is not sponsored. I just want to share what I think works really well for those travel often. Project Fi was a game changer for me. I was tired of paying stupidly high phone bills in Canada (one of the most expensive mobile phone markets in the world) and I was studying in the US so had all the requisite US based information. Although there have been a few announcements about plans for expansion, I'm still waiting for them to move into other countries, so for now you need a US address to get one of these plans.
Why is Google Fi so kick ass? Well it's $20 a month for the base plan, plus $10/GB anywhere in the world... yes, there is no extra charges for foreign data. Let me repeat that, NO DATA ROAMING CHARGES. This is huge! So for an average of 3 GB, you're paying $50/month to use your phone anywhere.
There are a few caveats to this of course; calls outside the US on the cellular network charges you $0.20/min, but you can call via wifi to avoid these charges. And even then, it's not bad for a few minutes if you're desperate. Calling to a number outside of North America will cost you, but the rates are pretty reasonable (you can check them here). But SMS messages are always free.
Where Can I Use It?
Surprisingly, almost everywhere. I have yet to visit a country where it didn't work at all (except Antarctica). Some countries have restrictions, such as no wifi calls in Argentina, but you can usually figure out a way to work around this. I've even had it work in countries where I wasn't expecting it to: I was prepared to spend 4 days off the grid in the Maldives but was surprised to find out I was still getting emails in the middle of the ocean... that could be a good or a bad thing.
Outside the US - Other Options
Sadly, this isn't an option if you're not based in the US (but hopefully it will be soon.) Definitely call your service provider to see if there is a package you can buy prior to going overseas. This varies by country, but if you can't get a good deal from your service provider, there are lots of wifi options for smart phones these days. Try to avoid the "pay as you go" plans where you're charged a daily fee for using your own minutes and data (I'm looking at you Canadian service providers) as these can add up quickly.
If you're going to be out of the country more than a few days you can either grab a mobile wifi device (for example, in Japan a lot of airbnb's include these in their price) or if you're there for more than a week, it might still be worth it to get a local sim card. In the latter case, make sure you have an unlocked cell phone (you can call your carrier to check if your device and get them to unlock it for you).