I had my mobile activated for the Security Key SMS. It worked fine until Dec 27, when I changed cellphone plans. (I upgraded my plan to unlimited voice & txt.) Since that date, I am unable to receive Security Key SMS from PayPal. I have successfully signed up my mobile for Account Notifications, and have received and sent SMS to many, many other numbers.
How do I get PayPal Security Key SMS to work with my cellphone again, it is a very valuable layer of security.
