Hi!
My ISP (SIPproviderA) also gives me 2 phone numbers via VoIP.
One ends with 2 and the other with 3.
My asterisk server (192.168.1.3 - it is behind a NAT and a SIP-ALG) registered both numbers with SIPproviderA.
I try to use the computer, that also runs the asterisk server, for simulating two fax machines at phone2 and phone3.
When I try to send a fax in T.38 mode from phone3 to phone2:
- my asterisk server sends an INVITE packet (from phone3 to phone2).
- then there is some traffic that looks ok…
- then my asterisk server sends another INVITE packet (from phone2 to phone3) (this seems to be the “re-invite” that the people talk about so often).
- then my provider sends “SIP/2.0 403 Forbidden”
sip.conf:
allow = !all,ulaw,alaw,gsm
canreinvite = yes
directmedia = no
faxdetect = yes
t38pt_udptl = yes,fec,maxdatagram=400
insecure = port,invite
[…]
extensions.conf:
[…]
same => n,ReceiveFax(${JOBFN}.ongoing,dfs)
[…]
same => n,SendFax(${TIFF},dfs)
[…]
how can i use T.38?
(that other fax mode (G.711?) is somewhat unreliable…
about 25% of the transmissions fail… or even 50%…)
why does asterisk send the keepalive packet multiple times in the same second to the same SIP server?
is it because the keepalive packets r sent per peer and not per UDP connection (i mean: the peers share the same UDP connection)?
Thx.
Bye
Arne
appendix: tcpdump and some log messages
http://www0.wgboome.org/t38,tcpdump.txt