The other party can receive text messages, but the mobile phone keeps reminding them that they are on the phone. Is it possible that the signal is bad?

Are you sure the other party can take your call? Maybe people don't want to answer your phone. There may be something wrong with the other party's mobile phone or the signal. Sometimes mobile phones play some online games, and messages or something may not get in. It is also possible that the other party's mobile phone has interception software such as incoming calls and Xin Anyi, or the mobile phone is poisoned (generally unlikely). It is most likely that there is something wrong with the mobile phone.