Just looked on their site and there are no regional plans listed any longer,
only national plans.  I guess that's why you got switched.

Are/were you former AT&T?  Still on an old AT&T plan?

You might want to double-check (and report back here, of course) and make
sure that any promos or special rates are still in place.  I had this issue
with my AT&T "GAIT" plan being force-migrated to GSM America National, but
they (at first) didn't want to maintain a comparable rate plan.

I also received the letter for the secondary line on my plan.  Here are
two exerpts:

"We've upgraded your regional plan to a national plan to give you the
best wireless experience.  This means you will not pay domestic long
distance or roaming charges for calls placed on the GSM America National
network.  Best of all, you don't have to do a thing - this change is
automatic and at no additional cost to you!  Plus, yo ucan talk for free
to 50 million Cingular customers now that you're part of the nation's
largest Mobile to Mobile calling community."

"We've lowered your Additional Minutes rate!  If you happen to go over
your monthly minutes, Additional Minutes are now only $0.35 per minute.  
It's just one way we're working to enhanve your wireless experience.  
Everything else in your rate plan remains unchanged."

Honestly, I'm not exactly sure why I got this letter because I'm
actually on the GSM America National plan with the North America
package.  I'll just keep my eye out for billing errors during the next 2
cycles in case my Canadian calls have long distance/roaming charges
(especially the ones in Canada).

TH