How to let user opt in again when user response STOP to SMS

Hi there,
When I verify send SMS API (https:// developers. zoom. us/docs/api/contact-center/#tag/sms/POST/contact_center/sms), message body automatically contains “Reply STOP to cancel. Reply HELP for help” at bottom.
When I reply STOP to opt out, and then all sendSMS to this number will rejected due to “This consumer number has opted out of receiving SMS from this Zoom contact center number”.
Now I have two issues on this:
1, How can I get user opt out immediately? Any WebHook event available?
2, How can user opt in again? Reply SMS or any function or API triggered manually?
Thanks.