The shock-absorbing wall structure can be used to equip transport containers which may suffer major falls, generating very high energy on impact. The invention detects the presence of an existing answering machine or voicemail system of a Recipient by listening for talk-over during playback of the message or initial prompts. The shutter blade includes a light shielding portion capable of moving across the aperture by rotating about a shaft formed on the base, a securing portion secured on the base, and an elastic portion connecting the light shielding portion and the securing portion. In addition, good recording marks can be formed without exceeding a maximum allowable recording power. Upon determining an insulation failure and the like between the electric charger and the electric vehicle, the electric charger data and the vehicle data are synchronized based on the time lag and then compared. Each of the second ends is attached to a bottom side of a vehicle roof.