Ios8.4 can be a perfect jailbreak. At present, the highest version supporting jailbreak has reached ios9, but A 1528 is Unicom version. Even if you jailbreak, you can't support mobile 4G, and the mobile card can only use 2G. The jailbreak method is as follows:

1, download a pp jailbreak assistant from the computer, install it and open it;

2. Open the settings of the mobile phone-General-iCloud. After entering, the function of finding my iphone will be turned off, and the screen lock password will be turned off;

3. The mobile phone is connected to the computer. After waiting for identification, click the Start Jailbreak button of pp Jailbreak Assistant, and wait for the completion of pp Jailbreak.