The term 'telephone sound' can refer to three different sounds associated with telephones: TONE (4 letters), RING (4 letters), and Bizetsignal (11 letters). TONE is a sound that is used to indicate the end of a call or to indicate that a line is busy. RING is the sound that is heard when a phone is ringing, usually a repeated pattern of two tones. Bizetsignal is a type of ringtone composed by Georges Bizet, which is often used as a default ringtone on many phones.