I used to have the phone line hooked up to my guitar amp in college, and used wake-up calls as an alarm clock this way. While the dialtone is maybe 10VAC, when the phone rings the line carries 90VAC; remember it has to actually power the ringer on the phone, not just the tiny speaker. You could actually see the center of the speaker hooked up to the amp moving by about a foot during this ring, and all the posters & stuff would shake right off of the walls in the room. This is definately a ringtone that won't disappoint.