"Yes, Vonage has a few more features I would like, and is $5 less;"
To which, a commenter, the mysterious SamIam, kindly said:
"AT&T CallVantage isn't $5 more than Vonage. Call them up and change your plan. The new plan (same as the old plan) is under $25 -- The FCC requires you change to the new plan!"
Well, I logged into my CallVantage account today, saw a link to change my plan, and was able to switch it to the $25 plan instead. There is NO difference between the $30 and $25 plans; just different price.
Thanks, SamIam: $60 a year savings, because of your comment!