How to set up personal hotspot in in iphone4 , ios 7.1 . The error is coming like (to set up personal hotspot in this account contact carrier)

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You are receiving this error because the carrier has to support Personal Hotspot and provision your account for it. So, check with your carrier and see if they support Personal Hotspot and if they do what do you have to do to qualify for it. Most carriers charge an extra fee for Personal Hotspot.