Why does my mobile phone automatically reply when the other party calls me?

Opening method of call waiting: standby page-mobile phone-menu key-call-other settings -sim 1/sim2- call waiting-open. After call waiting is turned on, when talking to A, B will be prompted at this time, and you can choose to keep or end. Note: Call waiting service needs your calling card support. It is recommended that you contact the network operator to confirm whether the calling card supports this function.