30 May
2008
30 May
'08
7:31 p.m.
Hello,
I am trying to configure a number of openser servers.
I have the following testbed:
Phone1 + Proxy - Registrar - out proxy
Phone2/
The Proxy acts as outbound proxy for customers and uses ienum to route
messages to the right registrar (using user@domain), the registrar then
figures out where the destination is and sends the packet out to
ENUM/PSTN or in my case back to the same proxy.
The proxy is running nathelper (and redirects rtp to an rtp proxy) and
performs route-recording.
The proxy configuration has:
modparam("path", "use_received", 0)
and the registrar configuration contains:
modparam("registrar", "use_path", 1)
modparam("registrar", "path_mode", 0)
modparam("registrar", "path_use_received", 1)
When registering all is fine and well and the packet flows like:
Phone<X> -> Proxy -> Registrar (storing in DB) -> Proxy ->
Phone<X>
and the DB contains in path:
<sip:ProxyIP;lr;received=sip:PhoneIP:PhonePort>
However, when performing an invite the ACK packet (INVITE/OK/ACK) can
not be routed properly as it is not part of the transaction, which
causes the call to be cancelled after a few seconds (as it should be
given the constance).
The ACK packet starts as
URI: <sip:user@<Registrar IP>:5060;rinstance=xxxxxx>
Contact: <sip:user@PhoneIP:PhonePort>
with the IP and Port correctly translated from the internal to the
firewall external.
It then travels like this:
Phone1 -> Proxy -> Registrar > Proxy <stop here>
When leaving Registrar the ACK URI has been changed to the one stored in
the DB path field ie: <sip:ProxyIP;lr;ftag=yyyyyy>
at that point the Proxy is not able to figure out where to forward the
packet even if the Contact field of the packet is still correctly set to
the IP:Port of the phone to be reached.
I was wondering if I am missing some understanding of how RFC3327 is
working.
I can see a few possible solutions:
- generate a first Path header with the Phone information on the proxy
before the current one.
- try to catch those 'out of transaction ACK' and set the URI to the contact
But before doing anything I would appreciate if someone could let me
know if I am attempting something idiotic from a design point of view
and tell me why what I expected to 'just work' does not behave as expected.
Thank you very much your your time and help.
Thomas