Method for assisting unregistered user device to access private network service and communication system

The disclosure provides a method for assisting an unregistered user device to access private network services and a communication system. The method includes steps as follows. A request to access a private service of a private network is sent by a user device. In response to determining that the user device not registered on the private network wants to access the private service, the user device is assisted to obtain a temporary user profile by a mobile edge computing server through an emergency type attachment procedure. In response to determining that the user device is registered on the private network through the emergency type attachment procedure, a regular attachment procedure is executed by the user device based on the temporary user profile. In response to determining that the user device executes the regular attachment procedure, the mobile edge computing server provides the user device with the private service.