Please give me the names/urls of 3 companies which have virtual
auto-attendant services but do not charge for call volume.

To answer this correctly, I need to have the name of 3 distinctly
separate companies and their website urls.  Also, the services must
only charge a single monthly fee for the virtual auto-attendant service 
with no other charges.  These must be completely virtual services 
requiring no equipment whatsoever.

You should know that I've already looked a number of services like:
Voiceshot.com
Packet8.net
Gotvmail.com

All of these charge per minute or have minute-bucket packages, which
make them terribly expensive and rather parasitic... i.e. they are
charging me for speaking on the phone not my core need which is the
auto-attendant / receptionist tool.

I want to find 3 offerings which simply act as a way-station which re-directs
calls to different numbers depending upon the callers needs, with or without
voicemail (not very important). I.e. Press 1 for Sales, 2 for Support,
3 for Mike, 4 for Mary, etc.

Ideally, these are priced reasonably in the $30 - $50 per month range,
but I'm open to slightly more expensive services, so long as the price
is a fixed, known quantity.