A cell phone uses a SIM card for mobile and data services. These days many phones are set up to take an eSIM. This is key to avoiding steep roaming charges when you travel. Be sure to turn off your data provider roaming when you take off.
Back in the day, you had to switch out the physical SIM card and install a local one when you land at your destination. It’s easy enough to do. You did have to have that little tool (or a paper clip) for your iPhone.
Recently, we went to northern Portugal for a week-ish and needed an eSIM for our day trips.
Since I used Airalo for my last international trip and it worked great, Airalo was my default. Plus my affiliate link allows personal bookings, which ironically I couldn’t figure out how and didn’t use.
For my Hong Kong trip, my Airalo eSIM worked perfectly. I had no problem on the MTR, its subway which goes both underground and aboveground. I had no problem on the ferry, taxi, car, in the Central or further out. I had data and I could call and text. It made coordinating with everyone so much easier, especially when I had to find the apartment after a long-haul flight.
In northern Portugal, my Airalo eSIM mostly worked great. In Porto, Braga, and other urban destinations. It wasn’t so great when I was at the famous and beautiful Sanctuary of Bom Jesus do Monte near Braga. WhatsApp messages were also delayed when I was in basement grocery stores. My in-laws chose Saily and could send messages at these places.
Airalo has gotten great reviews in Portugal so…
How much Data Do You NEed?
How much data was I going to need was something I researched as well.
Our vacation rental has wifi so I knew I didn’t need to rely on my eSIM. However, without an itinerary, I had no idea how much I would need. So just in case, I went with 20GB since I got a discount anyway. Instead of $18.50, I paid $15.72. I didn’t need 20GB AT ALL. 10GB would have been far from sufficient.
What I needed data was for day trips. Porto, Braga, coastal towns, Bom Jesus, etc. Because we toured these places together and didn’t break off on our own, there was hardly any need for data. I searched for a few things, like the stationery store I wanted to check out in Porto. Our longest day trip was to Porto, which was about four hours in the city. The train ride was about an hour each way, which we spent sketching. If I were streaming a movie or social media, I would have needed more data.
For basic map and internet searches, for a week in Portugal, 5GB is plenty if you have wifi where you are staying. A battery/mobile charger is more important if you take a lot of photos with your phone.
Both maps (navigation) and WhatsApp actually use very little data.
If you do want to stream movies, watch social media reels, videos or Tik Tok, or driving through Portugal, then bump up to 10 or 15GB. For most tourists, unlimited data is not necessary. I don’t post social media posts while on destination and leave any work I may have until I get back to my accommodations.
Below is information taken from the Airalo and Saily websites, correct as of July 26, 2026.
You can see that Airalo and Saily offer comparable prices, with Airalo giving more options. There is also very little difference between the 7-day and 15-day or 7/15-day and 30-day options with Airalo.
| AIRALO | SAILY | |||||
| USD | DAYS | USD | DAYS | USD | DAYS | |
| 3GB | $6.00 | 3 | $6.50 | 7 | $7.99 | 30 |
| 5GB | $7.00 | 7 | $8.00 | 15 | $9.99 | 30 |
| 10GB | $10.00 | 7 | $11.00 | 30 | $16.99 | 30 |
| 20GB | $18.50 | 15 | $19.00 | 30 | $27.99 | 30 |
| unlimited | $19.00 | 5 | $18.99 | 5 | ||
| unlimited | $27.00 | 7 | $26.99 | 7 | ||
| unlimited | $34.50 | 10 | $34.99 | 10 | ||
| unlimited | $48.00 | 15 | $48.00 | 15 |
Get your Saily e-sim
How to Set up Your E-sim
Installing your eSim requires internet connection.
Download the app for the carriers. Find your eSim and follow instructions to activate it.
You can also do it manually with information from the provider or via a QR code.
For iPhone:
- Go to “Settings”
- Go to “Cellular”
- Tap “Add eSIM”
- Go to the bottom of the screen and select “Enter information manually”
- Paste the eSIM information from the eSim provider
For Android:
- Go to “Settings”
- Go to “Connections”
- Tap “SIM manager”
- Tap “add eSIM”
- Select “Scan QR code” and then “Enter activation code”
- Paste the activation code shared by your provider.
Connecting to the network
Once installed, for an iPhone, you’ll also need to choose the eSim and turn on roaming for it. If part of the plan, you can also choose your eSim for voice and text. On an android, it’ll be the SIM Manager.