Iphone constantly reminds the main card to send information.

The cell phone signal is unstable, and the sim card of the cell phone is broken.

The mobile phone signal is unstable, which leads to abnormal information reception, which leads to the iphone always reminding the main card to send messages. At this point, you can try to restart your phone or change the network environment.

There is something wrong with the sim card of the mobile phone, so it can't receive messages normally. At this time, you can try to replace the sim card or contact the operator to check whether there is a problem with the sim card.