Can you turn cellular off for individual apps? Will it go into Airplane Mode? Have you tried Reset Network Settings? Go to Settings>General>Reset> Tap Reset Network Settings. You may need to enter your wifi passcode back in afterwards.
Sent from from my ancient but trustworthy iPhone 5
Looks like you're not the only one. Here's the same issue on another thread. It must be the jailbreak. Maybe a tweak causing the problem. Here's the other thread. http://forums.imore.com/showthread.php?t=293761
Sent from from my ancient but trustworthy iPhone 5