What's the matter with the main card sending a text message to accept cancellation?

1. Network problem: The receiver's mobile phone is in an area with poor signal, or there is a problem with the network connection, which makes it impossible to receive short messages normally.

2. Mobile phone settings: The receiver's mobile phone has set some options to filter or prevent receiving short messages, which causes the short messages sent by the main card to be intercepted or ignored.

3. Short message center problem: Sometimes, because the short message center is busy or broken, the receiver will not receive the short message temporarily.