The other party did not receive the SMS prompt.

It is more likely that the short message to the other party is not delivered in time. As follows:

1, the other party has stopped.

2. The other party's mobile phone is not in the service area.

3. The other party's mobile phone is not turned on.

After the undelivered SMS is deleted, the other party can still receive messages normally after its status is normal. However, there is time limit. After more than 48 hours, the message will be automatically deleted and the other party will no longer receive it.