The ringtone is at the level that you last used the phone on. If that is max volume in order to hear someone then the ringtone when the next person calls you will be at max.
I have one colleague that use a crappy headset and I have to turn the volume up every time I speak with him - if I forget to turn it down before I hang up (with him - no problems with others) I to experience the loud ringtone
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