The sound a phone makes when receiving a call; the tone heard by the caller's phone.
スマホの呼び出し音を変えた。
I changed my smartphone's ringtone.
ringback tone; ringing tone
The tone heard by the caller while waiting for the recipient to answer; often a standard beep or a custom melody.
呼び出し音が鳴っているのに誰も出ない。
The ringing tone is sounding, but nobody answers.