Nokia 9 PureView user guide
Dual SIM settings
If you have a dual SIM variant, you can have 2 SIMs in your phone. For example, one for your work and one for your personal use.
Choose which SIM to use
When, for example, making a call, you can choose which SIM to use by tapping the corresponding SIM 1 or SIM 2 button after you dial the number.
Your phone shows the network status for both SIMs separately. Both SIM cards are available at the same time when the device is not being used, but while one SIM card is active, when, for example, making a call, the other may be unavailable.
Manage your SIMs
Don't want work to interfere with your free time? Or do you have a cheaper data connection on one SIM? You can decide which SIM you want to use.
Tap Settings > Network & Internet > SIM Cards .
Rename a SIM card
Tap the SIM you want to rename, then type in the name you want.
Select which SIM to use for calls or data connection
Under Preferred SIM for , tap the setting you want to change and select the SIM.