Samsung SPH-A920 Phone Manual page 220

Can I make calls and use Sprint PCS Vision services at the same
time?
You cannot use voice and Sprint PCS Vision services simultaneously. If you
receive a call while Sprint PCS Vision service is active, the call will be
forwarded to voicemail. You can place an outgoing call anytime, but it will
interrupt any in-progress Sprint PCS Vision session.
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 flashes on your phone's display screen.
When is my data connection dormant?
If no data is received for ten 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 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
Vision in your phone's menu.
198 Section 3B: Sprint PCS Vision