How can a smartphone cancel a short message being sent?

There is no need to cancel. Text messages sent by mobile phones, the first time. It only takes one second to send a message when the signal is good. You can't cancel.

If you click Send to cancel when the signal is bad, you can immediately jump the phone to offline mode within a few seconds, and the message will not be sent. Then just delete the message in the sending mailbox. However, it is difficult to cancel the transmission. I still want to send it.

The only mobile phone that cancels SMS sending now is Huawei Glory 6plus. Here's how to cancel.

First of all, you need to upgrade the development version of rom, which is temporarily unavailable in the stable version.

Open the SMS app that comes with your phone.

Find the menu at the lower right of the main SMS interface (don't enter the secondary page) and select the last setting.

In the general section of the settings page, the third item is to cancel the sending function. In the latest version, it is cancelled by default, so we check it here.

After turning on the cancel sending function, you will come to the interface of sending information, as shown in the figure. After the message is sent, there will be a four-second countdown, which is the time for you to go back on your word.

At this point, double-click the message content to cancel sending, and the message content will return to the edit box and become a draft for later use.