The best replacement for doorbell is door bell.

The best alternatives to doorbell are rated as following:
★★★★★  door bell
★★★  wired
★★  buzzer
★  wired doorbell
★  knock
★  knocker

Your alternative for doorbell is not listed? Suggest!
Speaking about doorbell, one probably shouldn't forget about intercom.

Other search terms related to doorbell and their ratings are:
★★★★★ intercom
★★ intercom system
★ camera and intercom
You have in mind a companion for doorbell and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of doorbell in all years. Click on graph for more.
doorbell
door bell
wired