Firewall/NAT

[My setup]

I have an Asterisk setup at home and I'm not able to hear persons when they call me on FreeWorldDialup, however they are able to hear me. I have read where this is related to RTP ports that my Asterisk box uses (10000-20000) as defined in /etc/asterisk/rtp.conf file.

I have my m0n0wall configured with the following ports inbound to the my asterisk box

5060 SIP
4569 IAX
10000-20000 RTP

I initially assumed that outbound traffic would be NATted accourdingly, but I'm no longer of that opinion, so I would like to setup outbound rules coming from my Asterisk box to any based on the ports for SIP, IAX and RTP.

Can I do that without disabling NAT all together...

My setup
Internet <-> ADSL modem <-+-> m0n0wall <-> LAN<---->Asterisk

Asterisk,respectively the SIP Protocol(Without Extensions like STUN) is having huge problems with NAT.

A SIP Proxy on the Gateway(m0n0wall) should solve it all.
Or STUN support in Asterisk.
Or IAX Support at the SIP Service Provider

There does not seem to be a way, to get Asterisk running without problems behind a NAT-Solution (like m0n0wall) with NAT.

Sadly, many threads in Asterisk related forums testify that.

How would I setup a SIP proxy on m0n0wall?

Use advanced outbound NAT to disable source port re-mapping and see if that changes anything.

There's no SIP proxy available on m0n0wall.

I set the RTP ports in the rtp.conf from 18000 - 19000 opened it in m0n0wall.
Use ports 5060-5062 for SIP and 4569 for IAX2.
I have one connection to a local SIP provider here so I can call to the pstn and have normal phonenumbers, one to FWD (IAX2) and to another Asterisk server (IAX2). It work well and ich have no other phoneline anymore.

Regards Macro