The mobile phone number has been blacked out, will the short message show that sending failed?

It usually depends on whether the other party hacked you into a text message or a phone call. If you just blacken your mobile phone number so that you can't reach him, he can receive your message and won't be unable to send it.

1. If it's an Apple phone, you can't receive incoming calls and text messages, and you won't be prompted.

2. Not necessarily if it's an Android phone, because some Android phones can set up a blacklist of incoming calls and a blacklist of short messages separately. Even if the blacklist is set at the same time, some mobile phones can still set the "interception prompt" or set the interception prompt tone. Click the prompt to view the information content. If "Silent Interception" is set, incoming call records and new information will be automatically cleared without any prompt, depending on how it is set.