Has anyone had a problem with the auto confirmation text not sending to one particular client?

[Fluffit]

The particular client has been a monthly client for over a year. Her information has not changed. Last month when I noticed that she didn't confirm, I resent the confirmation text and received an error that it could not send the message. 

I verified all of her information and this month, the same thing is happening. 

It's only happening with this one client.

Please advise.

[MayaP]

Hello @Fluffit ,

I am sorry you and your customer are having issues with their confirmation texts. Can you provide me with the exact wording of the error? Or if you can upload a screenshot of the error message that would help!