http://bgr.com/2016/06/02/how-to-make-iphone-faster/

See here for an article which shows you how to do this.

Here are some codes you can dial into the phone app that will access hidden information and menus in the iPhone:

*#06# – Displays IMEI

*3001#12345#* + “Call” – Accesses a hidden Field Test menu

*#43# + “Call” – Displays call waiting status

*43# + “Call” – Enables call waiting

#43# + “Call” – Disables call waiting

*#21# – Displays call forwarding status

##002# + “Call” – Disables all call forwarding

*33*pin# – Enables call barring

#33*pin# – Disables call barring

#31#phone-number + “Call” – Blocks caller ID for the current phone call

*3370# + “Call” – Enables “Enhanced Full Rate” and improves voice quality on GSM networks (may impact battery life)

*#5005*7672# + “Call” – Displays your carrier’s message center phone number

Have you ever wondered how much data you should get with your carrier? Do you barely use your data plan but pay for a huge one anyways? Or do you go over data each month with your data plan and have no idea why? New in the iOS 7 Settings application is the ability to track cellular data usage per each app you have installed on your device. Read more »

http://www.cultofmac.com/16966/how-to-set-up-push-gmail-on-your-iphoneipod-touch/