Samsung M520 Owner's Manual page 202

Receiving an Incoming Call While Playing Your Music
An incoming call causes the currently played music file to be paused while
the phone call is active. Once the current call is ended, you can select to
resume any paused applications (music will resume playing automatically).
1.
Answer an incoming call by selecting Answer (
2.
When you are done with your call, press
previously paused application then resumes.
I
Note: When placing an outgoing call, the Application Manager pauses your
current music playback and allows you to proceed with your outgoing
call. When the call is ended, the Application Manger restarts the music
playback.
If the phone is running more than one simultaneous application (such as
Music Store, Mobile Podcast, Application [from My Content], and Games),
the user interface can begin to slow down and result in music or sound
interruptions.
Also, in some situations, the camera or camcorder may have limited
functionality or become unavailable. For example, if you were currently
playing music (via the Music Store), or playing a game in the background,
and then wanted take a photo, the phone may prompt you with a "CPU
Low, Kill the Application" dialog. This indicates that the current phone
resources are stretched and one of the current applications should be
terminated before continuing. Refer to the procedure above to exit either a
specific application or all current applications, and then launch the camera
or camcorder again.
176 Section 2J: Using Your Phone's Built-in Media Player
To solve this type of issue, it is best to close down all other
applications (Menu > My Content > Application Manager >
Options > Exit All Applications) before initiating a new
application.
).
to end the call. The