We are sorry this issue might be caused due to the local telecom operator. If you need further assistance to log in, you are suggested to submit bugs/software questions on Feedback via Settings/ Feedback on your device. And our technical team will reply to you in 2 working days after you submit the Feedback.
In order to prevent this case, we suggest binding an email address to your account as a secondary method for logging in to your account. You could bind your email address to your account on https://push.boox.com/