[Asterisk-Users] Setup/SIP routing

[E. Versaevel]

Hello,

I'm still kinda new to asterisk, but I'm trying to setup the following
situation:

Aterisk running at port 5065, SER running at 5060 (done that, works fine)

Load of SIP clients registering at SER (no problem), SER routing the SIP
traffic to Asterisk (no problem).

Incomming:
*) Asterisk registers at a SIP provider which sends SIP traffic to my host,
but not addressed to the registered user.
*) Asterisk has to pickup that sip traffic and relay it to ser at the same
host, but should not mess up the addressed user.
*) Ser performs routing (no problem here)

Outgoing:
*) SER sends outbound traffic to Asterisk (no problem)
*) Asterisk has to dial out to that number, but is challenged by my SIP
provider, asterisk answers challenge (should work by setting up a peer)

The reason for this setup is that my SIP Provider requires me to register at
his proxy (SER can't do that) and has to authenticate outbound calls (SER
can't do that either)

However, I'm having troubles routing incoming sip traffic to SER, asterisks
keeps messing up the form header (replacing it by the dialed context, ie
s at serhost )

Any ideas if this setup is even possible?

Kind regards, 

E. Versaevel