Hi.
I have a problem sending faxes from asterisk via t.38 protocol to analog fax.
Environment:
asterisk 10.8
spandsp 0.0.6.21
provider: easybell.de (supports t.38)
sip.conf:
qualify=no
disallow=all
allow=alaw
allow=ulaw
nat = yes
allow=g729
allow=g726
directmedia=no
srvlookup=yes
t38pt_udptl=yes
tcpenable=yes
transport=udptl,tcp
I am getting strange warning every time I want to send fax from asterisk to normal analog fax machine.
WARNING[10172]: res_rtp_asterisk.c:2158 ast_rtp_read: RTP Read too short
I have tested it with two different machines. With a fax machine from Philips I am getting this warning just once and then the fax receive starts and the fax gets received normally. With the second fax machine from Panasonic I am getting 20 or even more of those warnings and the line gets disconnected. The application I am using to send faxes is:
exten => 2,n,SendFAX(${FAXFILEPATH},fz)
here a piece of rtp debug log just before and after the fax transition with Philips fax machine:
[just before]
Sent RTP packet to 212.172.97.124:37762 (type 08, seq 041362, ts 760680, len 000160)
Got RTP packet from 212.172.97.124:37762 (type 08, seq 003325, ts 272932, len 000160)
Sent RTP packet to 212.172.97.124:37762 (type 08, seq 041363, ts 760840, len 000160)
[receiving fax starts]
[Sep 18 13:28:18] WARNING[10172]: res_rtp_asterisk.c:2158 ast_rtp_read: RTP Read too short
[receiving fax ends]
Got RTP packet from 212.172.97.124:37762 (type 08, seq 003333, ts 296456, len 000160)
Got RTP packet from 212.172.97.124:37762 (type 08, seq 003334, ts 296616, len 000160)
Got RTP packet from 212.172.97.124:37762 (type 08, seq 003335, ts 296776, len 000160)
Got RTP packet from 212.172.97.124:37762 (type 08, seq 003336, ts 296936, len 000160)
Can someone explain me what this warning means and why does asterisk behave differently with 2 machines. In second case the line gets disconnected 