How to automatically hang up when making a phone call with red rice?

The cell phone signal is not good and the battery is insufficient. According to the query, Zhongguancun is displayed on the Internet.

1. Bad cell phone signal: When the location is just in the signal blind area, the cell phone's mobile signal is weak or even absent, and the cell phone will automatically hang up or cannot be dialed.

2. Insufficient battery of the mobile phone: The mobile phone can't receive electromagnetic waves normally due to insufficient battery, resulting in the interruption of the mobile phone signal.