Samsung MM-A940 Owner's Manual page 247

Can I sign out of data services?
You can sign out without turning off your phone; however,
you will not be able to browse the Web or use other
Sprint PCS Vision services. While signed out, you can still
place or receive phone calls, check voicemail, and use other
voice services. You may sign in again at any time. To sign out,
go to Settings > Power Vision > Disable PCS Vision in your
phone's menu.
Section 3B: Sprint PCS Vision 221