Cell Phone Service Help for Traveler from US

She should go to a cell phone store in Brussels on arrival and buy a SIM with a 30 day plan. If it is anything like the UK or Italy, she’ll get 4 to 8 GB for about $50. It will be usable through out the EU with no roaming fees. She will need to renew it after 30 days which the vendor will be able to help her with.

If you are a Verizon customer, they have some good deals.
Just go to the Verizon website and you can customize the data plan for use in Europe.
They also offer unlimited texting from the US which was helpful for us.

First of all, have her install Google Hangouts (free app) on her iPhone right now, before she leaves. She can use Hangouts to make free phone calls to US numbers, even landlines, while on WiFi. (She could call EU numbers too with Hangouts but not for free - like Skype, it would cost a few cents per minute, and she'd have to buy credit.). She should install Hangouts now and try it - sometimes Google asks you to verify your existing cell number in the US to prove you have cell service, but once you do that, you can use Hangouts to make calls even without a SIM card, on WiFi, or with a SIM card using its mobile data.

Second, install some kind of free texting app like WhatsApp or Google Voice (Google Voice gives you a free US phone number, and it will work with Hangouts too if she wants to receive free calls from the US on that number.).

Finally, she should plan on buying a European SIM card. She can wait until she gets to Belgium - might make sense, because then she'll have a Belgian number (might be nice for communicating with locals while she's in Europe).

I haven't bought a Belgian SIM, but here's some info about them:

http://prepaid-data-sim-card.wikia.com/wiki/Belgium

EU roaming fees have mostly been abolished, but not every prepaid SIM even offers roaming - if it does, there will be no fee to roam in other European countries. She can just go to a mobile store in Belgium and have them set it all up for her. She may need her passport at the store to buy the SIM (many European countries require you to provide your identity to activate a SIM in their country - not sure about Belgium). Just make sure she asks them at the store about roaming.

If she has Sprint or T-Mobile now, they offer free unlimited roaming data overseas - but it's slow "2G" data. I just got back from Portugal and have Sprint, but I found the data too slow, so I topped up my Dutch Vodafone SIM from last year and use that instead - worked great. Some people find the "slow" 2G data acceptable to use.

She wound up getting a SIM from Orange today. 15 euro for 50 minutes, 4GB data and 4000 SMS. I'll have to figure out how the calls and sms work for Belgium vs intra europe vs US and have her use accordingly.

I tried loading the Belgium Be app, but it doesn't work without an Orange SIM. She has the app, but says can't authenticate. Perhaps that takes a bit of time. Data, sms and calls are all working though.

Is there anywhere on the Orange website where I could put in her phone number and see how much has been used so I know if she needs a top off? The site seems to only be in French or Dutch.

Will she be able to get fast data access with this Orange SIM in Netherlands, Greece, Macedonia and Italy for no extra charge?

We will use Facebook messenger as our primary way to communicate with her. She also has Google Hangouts working so she can call any number, though I haven't added funds yet.

I have an unlocked iPhone 7+ and just got back from Europe. I used my provider's (Sprint) international plan, which was free (sort of). I received free data and free texts and phone calls were .20 a minute. Now, having said that, if I had to do it again, I would opt for the high speed data plan that Sprint provides - this is $25 a week, but gives you high-speed data, free texts and free phone calls. The free data was not that fast (although for the most part, it worked fine - I really mostly used it for GPS on Google maps).

So if she wants to keep her same phone number, have her check with her cell phone provider to see what int'l plans they carry - otherwise, as others have suggested, she can get a SIM card when she gets there (or she can order it ahead of time), but she will have to use that phone number and not her own.

Sorry, just saw this post - try this link: https://topup.orange.com/

Belgium is not listed at that link. I found the link in French to top off, so no problem, but I'd also like to be able to monitor and see how much data, minutes and sms are left. Think she'll have to do that on her phone though as I can't find any way on the web to do that.

Also, looks like Macedonia is going to make things more complicated. No roaming there. She'll have to get another SIM there.

We have TMobile in the US, but I'm on an old plan and international data would be a lot. Best option is the Europe SIM. They do have a PC app called Digits where I think, when connected to WiFi, she can text and call from her PC using her us number for free. Not 100% sure, but we'll test it out.