Once it was a tech connecting some wires he shouldn't have (it's called a "bridge tap"). Essentially, there was a "Y" with one leg going to me and the other going up the street and open at the end. Of course an open end acts like a mirror. Strangely, it only acted up during certain hours.

Another time it was a misconfiguration at the Central Office.

Another time the repair guy stopped at the Central Office and did something, then came out here and tested, said nothing was wrong and charged me $60. It started working just before he arrived - just enough time to get in a van and drive here from the CO.

The most recent time was quite erratic. Before calling I went out and wiggled wires. Found the installer hadn't screwed down one of the binding posts tight and changes in temperature were causing the connection to make or break.