[asterisk-users] T38 Fax

[Robert Huddleston]

Thanks - and did you find a provider with T.38 DIDs? I don't see many pay as
you go providers with T.38

 

From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Larry Moore
Sent: Monday, August 01, 2011 4:08 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] T38 Fax

 

On 2/08/2011 1:02 AM, Robert Huddleston wrote: 

Anyone have any testing experience with T38 and HT-502 Grandstream?

 

I just want to confirm that t.38 is working on this device.

 

Thanks

 

 


Yes, it works.

I currently have latest firmware installed and it still works in T.38. I am
using UDP transport for this device as I seem to encounter problems with TCP
or TLS.

I am currently running Asterisk 1.8.5.0.


Product Model: 

  HT-502 V1.1C 


Software Version: 

  Program-- 1.0.5.5    Bootloader-- 1.0.0.9    Core-- 1.0.5.2    Base--
1.0.5.2


Some settings I have set and you may wish to check for the FXS port are;


Force INVITE: 

  (X) No     ( ) Yes (Always refresh with INVITE instead of UPDATE)


Send Re-INVITE After Fax: 

  ( ) No     (X) Yes 

 


VAD: 

  ( ) No       (X) Yes 


Symmetric RTP: 

  (X) No       ( ) Yes 


Fax mode: 

  (X) T.38 (Auto Detect)   ( ) Pass-Through 


Fax tone detection mode: 

  ( ) Caller   (X) Callee   ( ) Caller or Callee


Jitter buffer type: 

  (X) Fixed   ( ) Adaptive 


Jitter buffer length: 

  (X) Low     ( ) Medium   ( ) High 



You will need to ensure you are using redundancy mode instead of FEC.

I am able to send a fax via my voice provider seemingly without errors even
though ECM is not enabled, this is because redundancy mode is working as
expected on the outbound communication.

Unfortunately my voice provider only sends one data item in the incoming
UDPTL hence the occasional missed line.

Here is an extract from my sip.conf

[general]
.
.
t38pt_udptl=yes,redundancy,maxdatagram=400
.
.
[906]
; Grandstream HT502 FXS Port
; Analogue FAX Modem attached
type=friend
defaultuser=906
md5secret=c5bca943c9b0cc303c496fbf9d48a48e
call-limit=1
disallow=g722
transport=udp
qualify=yes
directmedia=no
host=dynamic
context=FAX-T38
faxdetect=no
deny=0.0.0.0/0.0.0.0
permit=10.0.0.0/255.0.0.0
permit=172.16.0.0/255.240.0.0
permit=192.168.0.0/255.255.0.0

Larry.

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