I have a telephone circuit (Model No. Panasonic KX-TS500MXB) which has following item between TIP and Ring. Do you have any idea what it might be? At first I thought it might be a back to back zener diode but after some testings I doubt if I am correct.
The following item is as well unknown to me. I have searched the part number but I couldn't find any item similar to this!!
EDIT: Here is the symbol that corresponds to first image: