Current AT&T customer and want to switch to prepaid plan with same number

You can't transfer numbers to AT&T that already are with AT&T. If you are changing from post-paid to pre-paid that is a migration within AT&T. 

In order to migrate to prepaid you have to do it in a corporate store.

And if you are trying to get one of the special $300 a year plans with 8 gig update a per month, you can only do that as a new customer unless you were willing to give up your number. If you want to Port out you can Port right back in again as a new customer to get the $300 plan.

Lizdance40, how do you port out? I have never heard of this before. We are currently not under a contract so we can leave at anytime.

Yes, we do want the $300 a year for 8GB plan. So would we just need to close out our current account and sign right back up? I worry that we would lose our current number that way. We do not want to lose our numbers. Or should we switch to mint mobile for a 3 month prepaid plan and then switch back?

To Port out of AT&T you need your current account number and security pin number and you take that information along with your phone numbers to a different carrier.   Do not cancel At&t service or you lose your numbers.  Only numbers with active service can be ported. 

You do not have to leave for a long time, people have switched out and switch back again in the same week.

Porting your numbers out to a new carrier automatically closes your at&t account for all of the numbers that you port out from AT&T.

Please be aware that AT&T, and all of the other carriers in the United States, do not prorate your final bill, you will pay for the full month service no matter when you change carriers.