Heywire? Where are my voice messages?

I have a gophone with AT&T, and I'm wondering, Where are the voice
messages people leave for me? In my phone or at AT&T?

Alternatively, why did Heywire start answering my phone when my phone
was off and someone called? And then why did the phone go back to
soliciting a voice mail (with no mention of texting or Heywire)?

When I bought the phone a year ago or so, I thought I wouldn't save
many pictures or any music at all, and didn't think I needed a memory
card. I planned to buy one anyhow but forgot.

I rarely use the phone but last week was an exception. Last week I
got maybe 6 voice messages, none of which I deleted. And starting
Saturday, Heywire.com was intercepting calls when the phone was off
and telling people they could text me. (Most of my friends don't want
to text, don't know how, and can't do it from the wired phones they
are usually using when they call me.)

By Monday the phone was back to working normally, even though I don't
think I deleted any voice messages (but the guy at Gophone customer
support thought the voice messages might be the problem.)


So, where are the voice messages stored? I assumed, since I had to
call a phone number to get them, they were on some AT&T server, not in
my phone. Better yet, when my phone is off, I can still call my phone
from another phone, put in * and my password, and listen to my
messages. So they must be at AT&T, right?

So what was going on with Heywire? Why was it intruding for two days.

(Neither the local nor the 800 customer service person had heard of
Heywire. That would make sense if memory was the issue and everyone
but me had plenty of memory, but if the messages are at AT&T, that
couldn't be it.)

Thanks.