Huawei Mate 9 Pro - Manual (Page 5)

4
Dual card dual standby single
pass
Your phone supports only dual card dual standby single
pass, which means you cannot use both SIM cards for calls
or data services simultaneously.
• When you are on a call using SIM card 1, SIM card 2
cannot be used to make or answer calls. If someone
calls SIM card 2, the caller will hear a voice message
similar to "The subscriber you dialed is out of the
service area" or "The subscriber you dialed cannot be
connected for the moment, please try again later."
The actual message will vary by service provider.
• When you are using SIM card 1's data service, SIM
card 2's data service will be disabled.
Your phone's single pass feature helps reduce power
consumption and increase your phone's standby time. It is
not related to your service provider's network conditions.
It may be a good idea to contact your service provider and
subscribe to missed call reminder and related assistance
services to avoid the conflicts mentioned above.