Speakers

To playback through iPhone speakers rotate the phone 180 degrees to hold it with speakers up.
Notice navigation bar tint changes to magenta:
http://a4.mzstatic.com/us/r1000/104/Purple/v4/f0/21/3c/f0213c32-4722-156f-37b1-def9cf91c4cb/mzl.rpvxrpwf.320x480-75.jpg
Now playback will be routed to speakers unless headphones are plugged in.

Note: rotation might be locked on iOS device.

iPad: Understanding the side switch

http://support.apple.com/kb/HT4085

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