A method for backing up and re-transmitting voice messages being transmitted during a call from a mobile device to an answering machine with a dedicated address in a network includes measuring the transmission quality between the mobile device and the answering machine while a connection is established between the mobile device and the answering machine, recording the voice message in the mobile device while it is being transmitted to the answering machine, after the call has ended and the mobile device has disconnected from the network, creating a data message in the mobile device containing the recorded voice message and the address of the called device, setting up a connection from the mobile device to the network, and sending the data message.