Samsung PM-A840 Owner's Manual page 224

Finding Your User Name
If you aren't sure what your Sprint PCS Vision User name
is, you can easily find it online or on your Sprint PCS Vision
Phone.
To find your User Name:
At www.sprintpcs.com. Sign on to your account using
your Sprint PCS Phone number and Password. To
display your User name, click on the My Personal
Information menu, then click on PCS Vision User Name.
On your Sprint PCS Vision Phone. You can find your User
name under the Phone Info option in your phone's
Settings menu (Menu > Settings > Phone Info> Phone
Number).
212 Section 3B: Sprint PCS Vision