Asterisk 1.4.17 + T.38 problem

Asterisk Asterisk Support
1

I had installed Asterisk-1.4.17 on Debian 4.0 (etch) using it since two months ago.

Recently, I required to do incoming and outgoing fax for SIP client.

I bought Grandstream HT-486 and Kapanga softphone.

I test following scenario:

Xerox fax machine—HT-486----Asterisk-----Kapanga
Xerox fax machine—HT-486----Asterisk-----HT-486—Panasonic fax machine

When I try to send/receive fax on scenario then it fail.

And I got

[Feb 17 11:38:30] WARNING[16454] chan_sip.c: Unsupported SDP media type in offer: image 5004 udptl t38
[Feb 17 11:38:32] WARNING[16454] chan_sip.c: Unsupported SDP media type in offer: image 5004 udptl t38
[Feb 17 11:39:42] WARNING[16454] chan_sip.c: Unsupported SDP media type in offer: image 5004 udptl t38
[Feb 17 11:39:45] WARNING[16454] chan_sip.c: Unsupported SDP media type in offer: image 5004 udptl t38

error message then fax call immediately dropped.

sip.conf:

[1100055]
type=friend
username=1100055
;secret=4321
nat=yes
faxdetect=both
host=dynamic
context=default
;defaultip=192.168.0.120
canreinvite=yes
callerid=1100055
mailbox=1100055@local
disallow=all
allow=alaw
allow=ulaw
;allow=gsm
;allow=g729
;allow=g723
t38pt_udptl=yes
qualify=yes

[1100056]
type=friend
username=1100056
;secret=4321
nat=yes
faxdetect=both
host=dynamic
context=default
defaultip=192.168.0.120
canreinvite=yes
callerid=1100056
mailbox=1100056@local
disallow=all
allow=alaw
allow=ulaw
;allow=gsm
;allow=g729
;allow=g723
t38pt_udptl=yes
qualify=yes

[1100057]
type=friend
username=1100057
;secret=4321
nat=yes
host=dynamic
context=towerfax
;defaultip=192.168.0.120
canreinvite=yes
callerid=1100057
mailbox=1100057@local
disallow=all
allow=alaw
allow=ulaw
faxdetect=both
;allow=gsm
;allow=g729
;allow=g723
t38pt_udptl=yes
qualify=yes

sip show peer

pbxCLI> sip show peer 1100057
pbxCLI>

  • Name : 1100057
    Secret :
    MD5Secret :
    Context : towerfax
    Subscr.Cont. :
    Language :
    AMA flags : Unknown
    Transfer mode: open
    CallingPres : Presentation Allowed, Not Screened
    Callgroup :
    Pickupgroup :
    Mailbox : 1100057@local
    VM Extension : asterisk
    LastMsgsSent : 0/0
    Call limit : 0
    Dynamic : Yes
    Callerid : “” <1100057>
    MaxCallBR : 384 kbps
    Expire : 53
    Insecure : no
    Nat : Always
    ACL : No
    T38 pt UDPTL : Yes
    CanReinvite : Yes
    PromiscRedir : No
    User=Phone : No
    Video Support: No
    Trust RPID : No
    Send RPID : No
    Subscriptions: Yes
    Overlap dial : No
    DTMFmode : rfc2833
    LastMsg : 0
    ToHost :
    Addr->IP : 122.254.125.12 Port 56197
    Defaddr->IP : 0.0.0.0 Port 5060
    Def. Username: 1100057
    SIP Options : (none)
    Codecs : 0xc (ulaw|alaw)
    Codec Order : (alaw:20,ulaw:20)
    Auto-Framing: No
    Status : OK (12 ms)
    Useragent : Grandstream HT487 1.0.8.33
    Reg. Contact : sip:1100057@192.168.0.173;user=phone

pbx*CLI>

pbxCLI> sip show peer 1100055
pbxCLI>

  • Name : 1100055
    Secret :
    MD5Secret :
    Context : default
    Subscr.Cont. :
    Language :
    AMA flags : Unknown
    Transfer mode: open
    CallingPres : Presentation Allowed, Not Screened
    Callgroup :
    Pickupgroup :
    Mailbox : 1100055@local
    VM Extension : asterisk
    LastMsgsSent : 0/0
    Call limit : 0
    Dynamic : Yes
    Callerid : “” <1100055>
    MaxCallBR : 384 kbps
    Expire : 97
    Insecure : no
    Nat : Always
    ACL : No
    T38 pt UDPTL : Yes
    CanReinvite : Yes
    PromiscRedir : No
    User=Phone : No
    Video Support: No
    Trust RPID : No
    Send RPID : No
    Subscriptions: Yes
    Overlap dial : No
    DTMFmode : rfc2833
    LastMsg : 0
    ToHost :
    Addr->IP : 203.91.112.200 Port 5060
    Defaddr->IP : 0.0.0.0 Port 5060
    Def. Username: 1100055
    SIP Options : (none)
    Codecs : 0xc (ulaw|alaw)
    Codec Order : (alaw:20,ulaw:20)
    Auto-Framing: No
    Status : OK (189 ms)
    Useragent : Kapanga Softphone Desktop 1.00/2166s+1203210879_0016D3B685E5
    Reg. Contact : sip:1100055@192.168.1.100:5060;transport=udp;rinstance=27F7788A27F77883
    pbxCLI> sip show peer 1100056
    pbx    CLI>

  • Name : 1100056
    Secret :
    MD5Secret :
    Context : default
    Subscr.Cont. :
    Language :
    AMA flags : Unknown
    Transfer mode: open
    CallingPres : Presentation Allowed, Not Screened
    Callgroup :
    Pickupgroup :
    Mailbox : 1100056@local
    VM Extension : asterisk
    LastMsgsSent : 0/0
    Call limit : 0
    Dynamic : Yes
    Callerid : “” <1100056>
    MaxCallBR : 384 kbps
    Expire : 650
    Insecure : no
    Nat : Always
    ACL : No
    T38 pt UDPTL : Yes
    CanReinvite : Yes
    PromiscRedir : No
    User=Phone : No
    Video Support: No
    Trust RPID : No
    Send RPID : No
    Subscriptions: Yes
    Overlap dial : No
    DTMFmode : rfc2833
    LastMsg : 0
    ToHost :
    Addr->IP : 122.254.125.12 Port 50878
    Defaddr->IP : 192.168.0.120 Port 5060
    Def. Username: 1100056
    SIP Options : (none)
    Codecs : 0xc (ulaw|alaw)
    Codec Order : (alaw:20,ulaw:20)
    Auto-Framing: No
    Status : OK (12 ms)
    Useragent : Grandstream HT487 1.0.8.33
    Reg. Contact : sip:1100056@192.168.0.170;user=phone

I tested 1.4.16/1.4.16.2/1.4.17 all same.

2

enable t38 globally in your sip.conf
t38pt_udptl = yes

3

What ITSP are you using to terminate your T.38 faxes?

4

Just I want to use T.38 within my Asterisk client, no any provider I am using for T.38.