SIP 2 SIP Not Working

[saitel]

1. Brekeke Product Name and version:
Sip Server 2.0.7.2

2. Java version:
j2sdk 1.4.2

3. OS type and the version:
Linux Centos

4. UA (phone), gateway or other hardware/software involved:
Linksys PAP2 / Eyebeam Soft Client

5. Select your network pattern from http://www.brekeke-sip.com/bbs/network/networkpatterns.html :
pattern 4

6. Your problem:
In my pattern the Router is represented by a Cisco PIX. I have some problem setting up completely Proxy:
- Sip 2 Sip are not working (only SIP to PSTN using an external gateway)
- Sometimes No-Audio/No-Ring Tone (especially using PAP2)

Do you have some suggestion to be applied for completing this setup?
Do you have some advice for configuring PIX firewall to allow RTP?

Thanks in advance
Max

[saitel]

Hi,
I solved the problem with RTP locked by the firewall but no hints on how to let SIP to SIP working.
I got a 404 not found when trying to call another SIP user registered.
Is something related to Dialplan?

Thanks
Max