I can now answer my own questions is someone else is wondering:

1. Do I need to configure anything more?

Gateways that use no authentication do not need to be configured at all. Simply attach the gateway to addresses when calling. For instance: sofia/default/+462311111@sipgw1.thegateway.com

2. How can I see if the registration to the gateway have succeeded

You cant for unregistered gateways, since they arent registered =)

3. Is it possible to debug just all proxy communication (and not all internal sip communication)?

Guess not. But you can set the SOFIA_DEBUG flag to 7, it will give you losts of information.

4. I trying to call with: "pa call sofia/mydomain.com/sipgw2.thegateway.com/4670123456", is that correct?

The command can currently not be used do dial profiles, only to dial stuff that exists in the dialplan. If you want to try your gateway add something like this: <extension name="5556"> <condition field="destination_number" expression="5556"> <action application="bridge" data="sofia/mydomain.com/+4670111111@sipgw2.thegateway.com" /> </condition> </extension> Replace +4670111111 with a real phone number (my provider uses E.164 format). If you want to dial using a registered gateway, the format is this: sofia/<profilename>/gateway/<number> This stuff will also be put in the user book that we are writing.