All that's left is the cancellation. On April 20th I switched over to cable-based Internet service. I've been very reluctant to do this since my last experience with this service (years ago) was abysmally poor. But the unreliability of my existing DSL circuit has left me no choice. There are only two DSL providers in my area (AT&T being one) and neither of them was able to make the service reliable.
My AT&T service would experience some sort of outage nearly every day. Many of the outages would last less than a minute, but there were frequent outages between 1 and 5 minutes, along with the occasional outage that would last 10, 30, 60 minutes or more. The record was two days.
Since switching to the cable service on the 20th I have experienced absolutely no outages. Which means that a ping attempted every 5 seconds during that time succeeded.
My original plan was to keep DSL for redundancy. But based on what I've seen in the last 10 days I don't think I need a backup.
Update: After closer scrutiny of the ping log I have discovered that I was a bit optimistic about my continuous connectivity. I have in fact had some pings go unanswered. Prior to today only one or two pings would get dropped at a time (5 to 10 seconds) except for one 25-second drop. Today it seems I have had three separate periods of time with 20 to 30 second outages. This is still far better than I was getting with AT&T. I just hope today isn't an early indicator of a trend.