iPhone 4S, cannot turn off 3G?

i noted friends 4s cannot turn off 3g service can on 4.

turn off 3g save power , limit cellular data between traveling wifi spots.

 

wirelessly posted (iphone 4s: mozilla/5.0 (iphone; cpu iphone os 5_0_1 mac os x) applewebkit/534.46 (khtml, gecko) version/5.1 mobile/9a405 safari/7534.48.3)

wait ios 5.1

 

Forums iPhone, iPad, and iPod Touch iPhone iPhone

• iPhone
• Mac OS & System Software
• iPad
• Apple Watch
• Notebooks
• iTunes
• Apple ID
• iCloud
• Desktop Computers
• Apple Music
• Professional Applications
• iPod
• iWork
• Apple TV
• iLife
• Wireless