If you are planning on using an "Unlocked GSM" phone... it is a little more complicated, especially if you want to use data. You will need to check what frequencies (bands) your phone supports. Then you will need to check what bands the different carriers are using.
FYI... the big carriers (Voda, Orange...) use Bands 3 & 7 for LTE, while Yoigo uses only Band 3 for LTE.
Yes, it might seem complicated, but luckily there is a website to make it easy...
https://www.frequencycheck.com/
NOTE: make sure you enter your exact model number (i.e. I have an LG v30, but they have several different models that support different bands) If you have an Android phone, just go to Settings--> About Phone -->Hardware Info and you can find the model number.
ALSO... if you are in the US, you might consider this sim card.
I used this one last year & it worked GREAT... 6GB and good for 90 days for $29!!!! NOTE: this is data ONLY. (I used a VOIP app for my calls/texts i.e. Viber, Skype...)
https://www.amazon.com/gp/product/B013EBUPDI/?tag=casaivar02-20
You might also checkout this sim card... 12GB data+3000 minutes+3000 texts for 30 days (NOTE:
I have not used this one, but it seems pretty good)
https://www.amazon.com/dp/B01FI1JW72/?tag=casaivar02-20
Hope this helps!!
Cheers,
-jj