HELP! Trixbox/Asterix Setup

OK.. maybe this has been done before and you can point me in the right direction. But I have
a question to the Gods of VOIP!

Currently we have a sales force that has dialup internet connection throughout the u.s. We
wish to use sofphones in the field (using 56k) most likely using g.729 codecs to connect to
a trixbox2.8/asterix1.6 server in house. We have a voip provider (broadvoice). But we would like to
allow our dialup empoyees access to the trixbox server (setup, on adsl 3/1.5mb, public ip)
to be able to make calls to our clients from our broadvoice account (our number).

I have gotten one softphone to communicate to another in the office. We have not been able
to get it working throughout the us.



ARE THERE ANY OTHER WAYS TO DO THIS?

client(dialup)<-----g729----->trixbox(t1+)<----->voip provider