Unicom's mobile phone can't break you out of prison. If you want to escape from prison, you have to do it yourself at the place where parallel mobile phones are sold. After the prison break, there is no guarantee. However, if there is something wrong with the machine, you can restore the official firmware, so you can guarantee it. 3GS is basically 3. 13 firmware now. In fact, these firmware are all upgraded by the government. Fixing some small vulnerabilities or preventing cracking has little impact on normal use. Unless the firmware is upgraded to above 4.0, there may be some functional changes.