There's a running joke for the millennial generation about how we're incapable of living without our phones for a substantial amount of time. And while this is mostly true for the sake of entertainment and communication to my social circle when I'm home, it is actually scary accurate when you're a study abroad student and traveling.
Personally, I got a new SIM card for my phone upon arriving in the host county of my study abroad program, so that I would be able to pay for a local plan and not deal with international fees while I was gone. While I was in my host country it was wonderful. However, wifi and data got a whole new meaning to me when I started traveling outside of my host country to other countries in Europe. While I would only leave for the weekend to visit these other places, it felt so much longer because you physically cannot use your phone at all in a different country. You have to keep it on airplane mode so it doesn't wrack up roaming data charges, you can't call or text off of it, and you can't use your wifi-operated communication apps unless you have wifi. I also learned that good wifi is rare in Europe.
Here's what that means for a traveling study abroad student:
We can't contact our families--or anyone at all for that matter--to let them know we're safe within the new country and we can't use the data on our maps app to find our way around so we have no way of figuring out where we are.
This meant that I couldn't contact my family members until I got to our hostel, hotel, or Airbnb and then when I left to explore for the whole day I often wouldn't be able to talk to them until I got back to where we were staying.
It also means that I had difficulty finding my way around without having the use of my maps app because it requires wifi or data in order to be used. Not only could we not type in an address and find a walking route, but a lot of times the map would have trouble loading in general so it wasn't even possible to find a route ourselves by looking at it. That's a scary and dangerous realization when you get to this new country and new city and realize you have no way of knowing exactly where you are or how to get around. When you're abroad, you can't take wrong turns at all or you could end up in a dangerous or secluded area where, if something went wrong, you wouldn't know where to go or who you could talk to.
Your phone becomes your lifeline when you're abroad. It keeps you tied to people back home and saved me countless times when I couldn't find my way around because I could just type in the address of where I was going into my maps and it would give me a walking route to get there. However, both of these functions weren't possible unless there was available wifi (or you had a data plan in the country).