[Asterisk-Users] Re: IAX calls dropout on button press

[Holger Schurig]

Grandstream Phones do have a bug where they sometimes send an UDP packet to
port 0 instead of port 5060. The effect is that you see 5 times the error
message

 WARNING4101: chan_sip.c:601 retrans_pkt: Maximum retries exceeded on call
 1c4b33fae3ec4116 at 192.168.233.67 for seqno 22209 (Critical Response)

on the asterisk box, because Asterisk sends some Command to the BudgetTone,
and the Budgettone answers, but to port 0. So Asterisk retries ... up to 5
times.

See http://www.voip-info.org/wiki-Asterisk+phone+grandstream+budgetone under
"Early Dial" (althought the bug appears with other SIP traffic as well).

For a crude fix, you can use the IP port redirection of Linux:

iptables -t nat -A PREROUTING -p udp -i eth0 --dport 0 -j REDIRECT --to-port
5060


-- 
http://www.holgerschurig.de