A missed call is signaled in different ways


In the call history list as an entry in red

An automatic activity can be created with the call result - Missed Call - (if configured)
For single matching records, the call activity will be automatically assigned to the found record.
An e-mail notification can be sent to the contact or account owner (if configured)

This feature can not be used if you are a member of a ring group where the group is setup up in a way that it rings for all group members. The call will be signaled for all members, and it would create a missed call for each group member not answering the call.