Modern phones, cell phones and smartphones with display typically feature advanced redial functions. This allows access to any number from a large redial memory. So you may access one of the last ten (or more) numbers dialed at the push of a button.
Even if a phone doesn’t have a redial button, it may possibly redial. After all, this function can not only be provided on the devices themselves, but also via switchboards or telephone systems. In this case a central server stores the last number dialed from a phone. A defined key sequence can then be used on a device to redial.