[Serusers] SIP TCP

mahesh mahesha at intoto.com
Fri Apr 1 07:54:53 CEST 2005


Hi ALex,

I am using the publicly available IPtel.org proxy server(195.37.77.99). The 
ALG is not coming into the picture when a call is initiated from 
HOST2(external). The SIP packets are not coming to the NAT device when a 
call is initiated from HOST2. The proxy server itself is sending,
  " 477 Unfortunately error on sending to next hop occurred(477/TM)" SIP 
message back to HOST2. So looks like some issue in the Proxy. Could you let 
me know the possible reason.


Thanks
Mahesh









Mahesh,

Most likely problem is that your ALG closes the translation port on
inactivity. If you are using cisco pix as an ALG, there is a way to adjust
inactivity timeout. I would also suggest getting the most recent version of
software.

Hope this helps

Alex

-----Original Message-----
From: <http://lists.iptel.org/mailman/listinfo/serusers>serusers-bounces at 
iptel.org [mailto:serusers-bounces at iptel.org] On
Behalf Of mahesh
Sent: Tuesday, March 29, 2005 7:21 AM
To: <http://lists.iptel.org/mailman/listinfo/serusers>serusers at iptel.org
Subject: [Serusers] SIP 477 error when registered with TCP

Hi all,

I am using the following network configuration.

HOST1---NAT---Internet---HOST2

HOST1 and HOST2 are windows XP machines with SJPhone software. The NAT box
has SIP ALG(Application Level Gateway), which modifies the SIP packets to
replace the Private IP address with the Public IP address.

I am registering with iptel.org proxy server using TCP from both the
machines. I am able to make a call from HOST1 to HOST2. But when i try to
make a call from HOST2 to HOST1, i get an error which says, "477
Unfortunately error on sending to next hop occurred(477/TM)". When I
register using UDP, then i do not see this problem. Could someone tell me
what I am missing here.

Thanks
Mahesh








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