You can talk with TCI and ask them transporter id. If they do not have transporter id, then you can ask for vehicle number.
You have to provide either transporter id or vehicle number.
In Karnataka E-way bill system transporter id generated in other state is not accepted. You take both state id and check.
To avoid frustration I will suggest to ask vehicle number. In 99% cases of my clients transporter id is not working.
chatCommentsThanks - Saurav Kumar