Transaction authentication numbers, TANs for short, are used to confirm operations in applications within the TU portal requiring extra security (also known as two-factor authentication ). Three different TAN procedures are in use:
- The TOTP procedure uses a smartphone app
that continuously generates TANs as needed after initial installation.
This is the simplest and most secure option and offers several
* can be used offline (no internet connection or cell phone service required)
* can be used abroad
* compatible with all smartphones
- The mTAN procedure uses your cell phone and generates the TAN needed for the operation, texting it to the registered device. Due to the high traffic some mobile network providers experience at peak times, you may not receive the mTAN in sufficient time to log into our services. Campus Management considers the mTAN procedure to be outdated and prone to failure. We recommend using TOTP as the standard procedure for two-factor authentication.
The iTAN procedure uses TANs and index numbers on printed or digital lists. Due to the benefits listed above, we recommend using the TOTP procedure.
You can register for the mTAN procedure during the provisioning
process or at a later point in the TU portal. To activate the mTAN
procedure, register your current mobile number in our system. To
confirm the phone number, you will receive a test text message at the
end of the registration procedure.
Every time you want to use a protected application in the TUB portal, a valid TAN will be texted to your phone within seconds, which you must then enter.https://www.campusmanagement.tu-berlin.de/?74276 
Managing the mTAN procedure
Step 2: If your account shows the message “Das Mobile-TAN-Verfahren ist ausgeschaltet” (The mobile TAN procedure is disabled), enter your mobile phone number and register it for the mTAN procedure by clicking on mTAN aktivieren (Activate mTAN).
Changing your mobile number
Step 1: To register a new mobile number, log into the TU portal and go to My Data > My Profile > TANs verwalten > Mobile-TAN verwalten and change the phone number. Finally, click on Mobilfunknummer ändern (Change mobile number). If you no longer use a phone number, you can first disable the mTAN procedure and re-activate it for your new number using your old TAN list.
Step 2: To register, an mTAN will be sent via text message to your cell phone which you must then enter in the next step.
Step 3: You will receive a message as well as an email confirming successful activation. After this any mTANs you request will be sent to the registered device. It is not possible to use both an old TAN list and the mTAN procedure at the same time. 
The iTAN procedure uses a printed list of TANs and index numbers which you received during the provisioning process.https://www.campusmanagement.tu-berlin.de/?74276