Samsung Galaxy Note5 User Manual page 170

When you use data services, your user name is submitted to identify you network. Your user name is
automatically programmed into your phone. You do not have to enter it.
Find Your User Name
You can find your user name through your phone's device menu.
1. From home, tap Apps
2. Tap Status.
You will see your user name under the "Username" heading.
Update Your User Name
If you choose to change your user name and select a new one online, or make any changes to your
services, you must then update the profile on your phone.
Messaging and Internet
> Settings > About device .
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