asterisk users - Jan 2016 - Virtual domain redirects

I run an ISP with virtual services.  We also offer VoIP.  Currently we
have our DNS set up so that virtual domains can have SIP addresses in
their own domain.  However, it comes to Asterisk as just the user
name.  For example, my SIP address is sip:darcy at VybeNetworks.com which
calls extension darcy.  That's fine because I am darcy in both the
virtual domain as well as the underlying ISP domain.  However, clients
can have whatever user name they want within their own domain.  For
example there might be a darcy at example.com that points to user dc2016
on our server.  That means that the client's sip address has to be
dc2016 at example.com.

I am trying to figure out how to allow darcy at example.com to be
translated to dc2016 at vex.net (out ISP domain) but I am at a loss to see
how it could work.  It almost seems like I need to run a separate
asterisk server for each virtual client.  Is there some sort of proxy
software that will let me do that more efficiently?  Is there some
magic DNS entries that can change it?

If it helps I am generating the configs from my client database for
asterisk as well as DNS so I don't care how complicated the configs get.

Thanks.

-- 
D'Arcy J.M. Cain
System Administrator, Vex.Net
http://www.Vex.Net/ IM:darcy at Vex.Net
VoIP: sip:darcy at Vex.Net

On Thu, 7 Jan 2016 00:04:05 -0500
"D'Arcy J.M. Cain" <darcy at Vex.Net>
wrote:
> I am trying to figure out how to allow darcy at example.com to be
> translated to dc2016 at vex.net (out ISP domain) but I am at a loss to
I think I see where I can hook this.

same => n,Verbose(0,To: ${SIP_HEADER(To)})

This shows me the actual address called.  e.g.
"To: <sip:darcy at vybenetworks.com>".  Now I just need to look
for a
place to grab this and put in a GoTo.  Perhaps a new incoming context
that does the lookup and then jumps to the existing incoming context.

-- 
D'Arcy J.M. Cain
System Administrator, Vex.Net
http://www.Vex.Net/ IM:darcy at Vex.Net
VoIP: sip:darcy at Vex.Net