[Asterisk-Users] SIP and VPN

[Mark Johnson]

Anyone out there got a SIP phone (mine's a Cisco 7940) to work through a 
VPN with a Netscreen 5gt?  It has always worked for me with any ScreenOS 
version 4.x.  I had the need to upgrade it to ScreenOS 5.x and it breaks 
the phone.  Here's the goofy part, it works enough to still register 
with the phone system and check if there is voicemail waiting.  But I 
get no audio on outbound calls.  Inbound calls seem to work OK.  The 
netscreen is not in NAT mode, but in route mode.  When the phone system 
talks to the phone at home, it uses the home LAN address.  In debug 
mode, the phone system doesn't seem to notice anything is wrong.

I don't know if this means anything or not, but...  On the phone system, 
if I do a "nmap -sU -p5060 <homephoneip>" it comes back with the port is 
open.  If I do the same thing from my home PC and nmap the SIP port on 
the phone system, it comes back "open|filtered" which I think means no 
UDP packet is returning.  SSH to the phone system works fine from home.  
I also noticed that NTP os broken on the phone, so something is wrong 
with UDP.

I found a really good article from someone having the same issues but it 
made no difference for me.  I have a support contract through Juniper, 
but they still have not found any resolution.  Here's the sip.conf 
section.  I tried some variations with canreinvite and some things, but 
it didn't help.  This has worked for me over a year like this.  Anyone 
got any ideas?  Thanks!  Mark

[1426]
type=friend
username=123456
secret=123456
host=dynamic
;canreinvite=no
;disallow=all
;allow=ulaw,alaw
;dtmfmode=inband
;nat=never
context=office
mailbox=1426 at home
linelabel="First Last"
callerid=First Last <1426>
line => 1426