Why can't my mobile phone activate Unicom voice mail client?

At present, it is found that some models will not be able to activate Unicom voice mail client. It is recommended to check whether the data network and WIFI of the mobile phone are available, and ensure that the Sim card of the mobile phone is in a normal state (insufficient balance, overdue downtime, etc.). ); In addition, the authority management of the mobile phone system itself or the installation of third-party security software such as mobile phone security manager and LBE security manager will block the sending authority of Unicom voice mail, and there will also be prompts that cannot be activated.