The main reason is that the permissions of the software are different, and the signed version has higher permissions than the unsigned version. For example, the unsigned version of mobile QQ will prompt "whether to allow network connection" every time it goes online, while the signed version can choose "always allow" to cancel this reminder when it is requested for the first time. In addition, the signed version of mobile QQ also supports file transfer function.

Whether you can download and install the signed version of mobile QQ depends on whether your mobile phone supports signing. If the download prompts "Invalid Certificate" or "Operation Failed", it means that your mobile phone does not support installing the signed version of mobile QQ. It is recommended that you download the unsigned version.