[Serusers] SER and Voip Provider integration for call PSTN phones

[pistara_bros at tin.it]

I'm looking for SER "uac modules", but how to configure ser.cfg to use 
it? 
Could anyone help me?
Thanks.


>>
Hi to all,
I have deployed SER 
on public IP, and i can install a communication betwen two IP Voip 
client.
Now i want configure SER to call , from a IP VOIP Client, PSTN 
phone number.
I' havent a PSTN gateway but I have a Voip Provider 
Account (Eutelia www.eutelia.it) 
that require authentication in order 
to call PSTN phone.
I'm studing the PSTN configuration reported in SER 
getting start (http://siprouter.onsip.org/doc/gettingstarted/ch09.html)

It describe how to use rewritehost("XXX.XXX.XXX.XXX") to specify the 
PSTN GATEWAY IP ADDRESS, 
but doesn't specify nothing about 
authentication.
 
The question is :
Because i havent a PSTN gateway,
It' is possible to configure SER in order to redirect PSTN call to a 
VOIP provider 
or It is necessary to use Asterisk between SER and the 
Voip Provider ?

Any suggestion about ser configuration would be 
appreciate.
Thanks in advance.