Huawei P9 Lite - Manual (Page 19)

First Use and Initial Setup
12
Dual SIM settings
When two SIM cards are inserted, only one SIM card can be set as the 4G/3G/2G SIM.
The other SIM card slot only supports 2G networks. You can also configure the default
card for mobile data and phone calls according to your monthly plan.
This feature only applies to dual SIM phones.
Open Settings and touch Dual card management. You can configure both SIM cards
as desired.
• If you disable a SIM card, you will be unable to use it to make calls, send messages,
or access the Internet.
•
Select Dual SIM calling. You can configure whether you want to select a SIM card
manually or use the default SIM card each time you make a call. If you choose to
use the default SIM card, your phone will use that SIM card for all outgoing calls.
Enable or disable a SIM card
Select 4G/3G SIM
Select default SIM for data services
Configure SIM settings for phone calls