I need to re-activate Duo Mobile. If you have a new phone (or have done a factory reset on an existing phone) and have kept your phone number, you will need to re-activate the Duo Mobile app. Your options here depend on what devices you have on your account. If you cannot log in to your account using an alternate means, you will need to reach out to the UT Helpdesk for identity verification and assistance. click here if you would like to print a copy of this document for your office!) I need to add an additional phone number. I want to change my default phone.