Error Code 403 is a general error code and generally all error codes are not logged with an actual reason. Normally, an error can give a range of error codes (for example when your browser cant connect you may see the common error 404: Not Found) 404 Not Found is REALLY general. What can it not find?! Unless you scroll through and read scripting or debug files line by line, you may never know. But, error codes are given a reason with certain variables or parameters. For example, Not Found is the problem type, variables can be 'No connection' so it may display error codes 400-405, each error between 400-405 can be a different variable.
In your case, a Verizon account can only have a few States.
Suspend (Switch Only)
Suspend (Switch and Billing)
So, ensure your account is up to date and that it is in a active state. If it is, then you will most likely need to call in to customer service (*611 or 800.922.0204)
Hope I helped!
MLD1217, Glad I could help. Please remember the only state that you would not be able to sign into the Verizon account is in a Deactivated state. If you are able to sign in on your tablet but not on the phone, ensure WiFi/Data is functioning properly. You may even want to try to reset your MyVerizon Password.