A special dialing feature was busy redial:
"If the number you are calling is busy, Busy Redial will redial the last local telephone number you called for up to 30 minutes. If the number is not available after 30 minutes, the redialing is cancelled. You can cancel the redial with a code if you do not want to wait for the number to become available."
I found this feature very handy when I had to make an urgent call to a line that was busy.
However, according to the Verizon web page, this feature has been discontinued for new customers. Could anyone explain why?