Ex employees continue to receive Statuspage notifications

[Cam Briggs]

I have setup status page for my business, I allow users to subscribe to email and SMS incident notifications.

SMS only captures the phone number that has subscribed, and we don't capture staff person mobile numbers so I have no way of knowing who the numbers belong to.

When a staff member leaves the business, we can't remove them from the sub list as we don't know who owns the numbers as status page doesn't capture any other data about the person, once they've been offboarded from our SSO they can't unsubscribe from the unsub link in a status page alert SMS as they hit a login wall.

Has anyone else run into this problem? Any suggestions on how to handle? 

EDIT: I've tested sending STOP, which appears to work. But the notification doesn't contain an instruction to send STOP to opt out, can i edit the SMS to include this?