Configuration help needed for Cisco 7905

My configuration is like this one:

http://siproxd.sourceforge.net/siproxd_guide/siproxd_guide_c7s3.html

However my phone is different; it's a Cisco 7905.  The relevant settings that the phone allows me to configure are these:

UID	 cisco
PWD	 mypassword
Proxy	 my.sip.server.net
SIPRegOn     1
SIPRegInterval	 3600
StaticIP    192.168.15.122
OutBoundProxy	 192.168.15.200 [my siproxd machine]
StaticRoute    192.168.15.1 [my dumb masquerading router, with siproxd set as the DMZ]

Here is my configuration for siproxd:

if_inbound  = eth0
if_outbound = eth0
host_outbound = name-that-resolves-to-my-external-ip.net

It doesn't work, here is what happens:

15:31:35 INFO:siproxd.c:233 siproxd-0.8.1-53 i486-pc-linux-gnu starting up
15:31:35 INFO:plugins.c:112 Plugin 'plugin_logcall' [Logs calls to syslog] loaded with success, exemask=0x40
07:31:35 INFO:rtpproxy_relay.c:121 Current thread stacksize is 8192 kB
07:31:35 INFO:sock.c:131 bound to port 5060
07:31:35 INFO:siproxd.c:344 siproxd-0.8.1-53 i486-pc-linux-gnu started
07:31:57 INFO:plugin_logcall.c:126 Outgoing Call: cisco-pU0pTbRKGX/[email protected] -> 888123456-pU0pTbRKGX/[email protected] [Req: 888123456-pU0pTbRKGX/[email protected]]
07:31:57 INFO:plugin_logcall.c:126 ACK Call: cisco-pU0pTbRKGX/[email protected] -> 888123456-pU0pTbRKGX/[email protected] [Req: 888123456-pU0pTbRKGX/[email protected]]

Also by using ngrep I see this:

interface: eth0 (192.168.15.0/255.255.255.0)
filter: (ip or ip6) and ( port 5060 )
#
U 192.168.15.122:5060 -> 192.168.15.200:5060
REGISTER sip:my.sip.server.net SIP/2.0.
Via: SIP/2.0/UDP 192.168.15.122:5060.
From: sip:cisco-pU0pTbRKGX/[email protected];tag=3840067541.
To: sip:cisco-pU0pTbRKGX/[email protected]
Call-ID: [email protected]
CSeq: 1 REGISTER.
Contact: Jeremy Malcolm <sip:cisco-Q0ErXNX1RuY/[email protected]:5060;transport=udp>;expires=3600.
User-Agent: Cisco-CP7905/1.01-030807A.
Allow: ACK, BYE, CANCEL, INVITE, NOTIFY, OPTIONS, REFER, REGISTER.
Content-Length: 0.
.

#
U 192.168.15.200:5060 -> 192.168.15.122:5060
SIP/2.0 408 Request Timeout.
Via: SIP/2.0/UDP 192.168.15.122:5060.
From: <sip:cisco-pU0pTbRKGX/[email protected]>;tag=3840067541.
To: <sip:cisco-pU0pTbRKGX/[email protected]>.
Call-ID: [email protected]
CSeq: 1 REGISTER.
Content-Length: 0.
.

#
U 192.168.15.122:5060 -> 192.168.15.200:5060
INVITE sip:88812346-pU0pTbRKGX/[email protected];user=phone SIP/2.0.
Via: SIP/2.0/UDP 192.168.15.122:5060.
From: Jeremy Malcolm <sip:cisco-pU0pTbRKGX/[email protected]>;tag=816758886.
To: <sip:88812346-pU0pTbRKGX/[email protected];user=phone>.
Call-ID: [email protected]
CSeq: 1 INVITE.
Contact: Jeremy Malcolm <sip:cisco-Q0ErXNX1RuY/[email protected]:5060;transport=udp>.
User-Agent: Cisco-CP7905/1.01-030807A.
Allow: ACK, BYE, CANCEL, INVITE, NOTIFY, OPTIONS, REFER, REGISTER.
Expires: 300.
Content-Length: 262.
Content-Type: application/sdp.
.
v=0.
o=cisco 15826 15826 IN IP4 192.168.15.122.
s=Cisco 7905 SIP Call.
c=IN IP4 192.168.15.122.
t=0 0.
m=audio 16384 RTP/AVP 18 8 0 101.
a=rtpmap:18 G729/8000/1.
a=rtpmap:8 PCMA/8000/1.
a=rtpmap:0 PCMU/8000/1.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.

#
U 192.168.15.200:5060 -> 192.168.15.122:5060
SIP/2.0 408 Request Timeout.
Via: SIP/2.0/UDP 192.168.15.122:5060.
From: Jeremy Malcolm <sip:cisco-pU0pTbRKGX/[email protected]>;tag=816758886.
To: <sip:88812346-pU0pTbRKGX/[email protected];user=phone>.
Call-ID: [email protected]
CSeq: 1 INVITE.
Content-Length: 0.
.

#
U 192.168.15.122:5060 -> 192.168.15.200:5060
ACK sip:88812346-pU0pTbRKGX/[email protected];user=phone SIP/2.0.
Via: SIP/2.0/UDP 192.168.15.122:5060.
From: Jeremy Malcolm <sip:cisco-pU0pTbRKGX/[email protected]>;tag=816758886.
To: <sip:88812346-pU0pTbRKGX/[email protected];user=phone>.
Call-ID: [email protected]
CSeq: 1 ACK.
User-Agent: Cisco-CP7905/1.01-030807A.
Content-Length: 0.

Interestingly there is no sign of "name-that-resolves-to-my-external-ip.net" above.  I have tried running a similar command on my.sip.server.net (because it's my own SIP server running yate), but it never sees anything.

Also interestingly, I have sip softphones on the same network which work fine, even without using siproxd as the proxy.  I guess they are a bit smarter about NAT, and can work fine even though my router does not have a sip ALG built-in.

Any help appreciated...

PS. Public IP addresses/domains have been changed for privacy/security reasons.

--
Jeremy Malcolm PhD LLB (Hons) B Com
Internet and Open Source lawyer, consumer advocate and geek
host -t NAPTR 5.9.8.5.2.8.2.2.1.0.6.e164.org|awk -F! '{print $3}'




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