TPG will provide you with a new pre-configured modem with your TPG NBN plan. You can track your installation here http://www.tpg.com.au/support/trackmyorder.
Once the service has been installed, I would suggest contacting DODO to ensure that the service has been cancelled.
Welcome to TPG Community!
If you failed to notify DODO to disconnect your account, then it will remain active even though your TPG account is already activated.
For our NBN Plans, we do provide a free modem for our clients which is configured to work with the bundled home phone.
Please coordinate with DODO to prevent any future issues on the account.
If the modem provided by DODO is not locked with them, then yes, it should work. We just need to change the configuration of your modem with your new TPG account information.
Once the ADSL2+ is installed, our tech team can guide you with set up to make the internet work with your current modem.