How to Customize Message Reply With SMS
Personalize the quick replies to send to an incoming call if you cannot pick up a call to make a more personal approach. Read on to learn how.
Note: Check your phone's ColorOS version in [Settings] > [About Phone] / [About Device].
Edit quick message reply
For ColorOS 6.1 and above: Go to the [Phone] app > tap the
icon > [Reject with SMS], then tap any of the existing messages to replace with a new message, then enter your preferred message and tap [Save].
For ColorOS 5.2 to ColorOS 6.0: Go to [Settings] > [System Apps] > [Call] > [Respond with SMS], then tap any of the existing messages to replace with a new message, then enter your preferred message and tap [Save].
For ColorOS 3.1 to ColorOS 5.1: Go to [Settings] > [Call] > [Respond with SMS], then tap any of the existing messages to replace with a new message, then enter your preferred message and tap [Save].
For ColorOS 3.0: Go to [Settings] > [Call] > [Reject with SMS], then tap any of the existing messages to replace with a new message, then enter your preferred message and tap [Save].
To reset:
Tap 
at the bottom to reset the messages to default.
OPPO Phones with Google Phone
Go to the [Phone] app > tap the [three-dotted] icon > [Settings] > [Quick responses], and tap any of the existing messages to replace with a new message, then enter your preferred message and tap [OK].
To reset: Go to the [Phone] app > tap the [three-dotted] icon > [Settings] > [Quick responses] > [three-dotted] > [Reset].
Related article:
* Pictures, settings, and paths might differ from those of your phone, but these won't affect the description in this article.