Or this: http://www.google.com/support/forum/p/voice/thread?tid=56a63...

Before you change to Google Voice for voicemail, please note there is no way to make GV pick up on the first ring. If a call 'times out' from your cellphone it will then ring another few times on GV EVEN IF YOU HAVE DO NOT DISTURB ENABLED. With my phone the wait is so long it's impractical to expect callers to hold on for it.

Please understand, I think GV is primarily good but for many of us this 'lack of feature' is a deal breaker.

Dial this: * 002 * 6175551212 # ... replacing the second string of numbers with your own. That should direct your caller to Google Voice messaging for busy/unreachable/no-answer on your iPhone (or other GSM network) but will still give you plenty of time to answer the call as usual.

Couple of things:

1) I think the above code needs to be 004 instead of 002. I tried 002 and it forwarded a normal call to google vm. 004 is for all conditionals (ie IF busy, IF, unreachable,...) and 002 is for "all 4" which seems to be just all the time.

2) If someone calls your cell phone and you're busy or don't answer, then they get redirected to google voice, google voice will then try to call your cell phone if you have that configured, so that's one hell of a confusing round trip for your callers.

Same experience here. I got the forwarding working, but the callback from GV to the iPhone is pretty frustrating.

So ##002# will cancel and return to AT&T VM?

No, it will cancel voicemail altogether. The phone will ring indefinitely, or eventually disconnect.

To return to AT&T VM, you'll need the phonenumber for that, which should be possible to obtain with #002#, then re-set with 002*(AT&T VM number)#

I'm not sure if I'll be trying that. ;)

Actually, it did reset to AT&T. I tried a few of these playing around.

Phones normally have these configuration features built in, in my experience. That is, you go into the configuration menus, and you can query and reassign your call forwarding settings.