If you have dual SIMs, you can select a default line for different functions like data, calling or texting. None of these functions have to use the same line and you can actually specify a default for each. Read on to learn how.
Calls and SMS
To set REALLY as the default calling or SMS line on Android:
Go to Settings and tap on Network & Internet, Wireless Networks or Connections to set the correct network preferences
Open SIM Cards, Dual SIM Settings, SIM Manager or SIMs
At the top of this screen, you can see the two SIMs inside your smartphone and their status. The rest of the screen displays other Dual SIM settings, which can be grouped in sections like Preferred SIM for and General Settings on certain Android devices
Select Calls, Default Calling Line, SMS or Default SMS line
A menu should pop up, and you can decide which SIM card you want to use as the default line when you make a call
Note: If you don’t choose a default card for this option, Android prompts you to choose the SIM every time you initiate a phone call.
Data
To set REALLY as the default data line on Android:
Go to Settings and tap on Network & Internet or Wireless Networks
Open Dual SIM Settings and decide on your preferred SIM for connecting to the internet
Since you can only have one active data connection, you have to set a preferred SIM for cellular data or a default mobile data SIM card
Depending on your phone, press on the option to change the default SIM to REALLY's Mobile’s eSIM. On the next screen, tap on a SIM to select it or confirm your choice by tapping Switch
Note: If your data isn’t active (since only one data network can be active in a particular moment) a toggle that says “switch data automatically” will show up. If the default network doesn’t respond, your Android will try to use the next option.
We always recommend researching how to add your new eSIM as a default SIM to your specific Android if the above steps don't work.