有著同樣的困擾,到 Apple Support Communities 找解答,以下是我使用一位 jsoto88,所回覆的方法!有相同的朋友,可以參考,也許可以幫忙!...Good Luck.
Re: 3G Issue IOS 6.1 - Iphone 5 2013/1/30 上午 7:26 (in response to nath.02.28) I had the same problem in Mexico, and I found a weird but effective way to solve the problem:
Go to Settings -> Carrier and disable the 'Automatic' feature. Then wait a few seconds and select your carrier. Enable the "Airplane Mode" Disable the "Airplane Mode" Restart your phone