This invention discloses a device and a method for end-to-end ciphered communication between wire telephones and cell phones. A MODEM module of the device is connected with the wire phone net, GSM module is connected with GSM net, the exchange module is connected with MODEM and GSM module, a control module is connected with the MODEM, exchange and GSM, a power supply module provides working supply to the modules. The secure communication is realized by the following steps taking the wire phone secure set as the calling party: 1, the calling party dials the gateway access number and a called cell phone number, 2, PSTN exchange provides the dial number to the gate, its MODEM extracts the number to the control module, 3, the control module calls the cell phone by GSM net, 4, the cell phone sends a response to GSM module to set up GSM communication, 5, the control sends the response to the server set to set up PSTN communication connection, 6, the control module controls the exchange module to connect MODEM and GSM modules for secure communication.