Originally my cellular plan cost 40 dollars per month with 6GB of data, which was a good deal if all that data were used. I do not travel outside the campus and the dorm very often. 6GB data seemed too much.
Plus I was being constantly bombarded by the Google Fi advertisement on YouTube. Since I do not need all that much data, Google Fi seems to be a good choice for only 20 dollars a month plus 10 dollars per GB of data if I use the data.
Google Fi has global coverage and charges the same as in U.S, except making phone calls and texting messages. But still, the price is reasonable.
A few notes for those who want to change to Google Fi:
Cancel any contract or auto renewal with the previous carrier.
Contact the previous carrier for account number and PIN to unlock number transfer.
When registering with Google Fi, select eSIM if supported. At the moment it is not possible to switch from SIM to eSIM after registration.
iPhone only supports T-Mobile for now. Google Fi can switch among carriers on Android phones.
May not be able to tether outside U.S.