How about settings like calenders, reminders, voicemails, messages. Does it remind you when one of those come and incoming calls if you don't hear it right away?
any other phones i had there was a bip or ring reminder in case i did not heard it the first time. when you are busy working, i don't think many people always look at their screen just to see if there is something new especially when you are in business. and in my first question i should have included e-mail as well