Samsung SPHM520 User Manual page 171

When is my data connection active?
Your connection is active when data is being
transferred. Outgoing calls are allowed; incoming calls
go directly to voicemail. When active, the or
indicator animates on your phone's display screen.
When is my data connection dormant?
If no data is received for 10 seconds, the connection
goes dormant. When the connection is dormant, voice
calls are allowed. (The connection may become active
again quickly.) If no data is received for an extended
period of time, the connection will terminate.
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 Power 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 > More...
> Data > On/Off in your phone's menu.
Section 3B. Sprint Power Vision 155