Autodialers (or auto dialers) are automated outgoing telephone systems programmed to dial down a list of telephone numbers sequentially. This tool is used to convey promotional offers and other marketing messaging. If no one answers the call, an autodialer will hang up and move to the next number on the list, and if someone does answer it will either play a recorded message or transfer the call to an agent. Autodialers that immediately connect to a call center agent are called predictive dialers.
When autodialers reach a recipient with a recorded message, either live or voicemail, it's called a robocall. Robocalls are placed to targeted recipients by automated calling systems programmed to broadcast a message out to a list of telephone numbers all at once. Some vendors refer to these calls as "voice broadcasts" because they are recorded messages sent to a large group at once, not sequentially.