[asterisk-users] t.38 fax over IAX2?

Benoit Panizzon benoit.panizzon at imp.ch
Mon Jan 25 03:44:03 CST 2016


Let's assume we have this situation:

Call => SIP TSP => Asterisk1 => IAX2 => Asterisk2 => SIP/ATA => Fax

I have two Asterisk Servers in two branch offices, which are
interconnected by IAX2 and the Switch functionality.

Asterisk1 is connected to the public phone network via a SIP provider
which supports T.38

A fax is connected to a SIP T.38 capable ATA Box.

If that fax is connected to Asterisk1, then the call is transparently
routed and received by this ATA box in T.38 mode.

If the fax is connectd to Asterisk2, then there is a IAX Link between
the originating SIP T.38 Fax and the Destination which is also T.38
capable. But T.38 is refused by Asterisk1. Fax receptions falls back to
g711 (sometimes) and is unreliable behind Asterisk2.

Google hints to me, that T.38 fax reception over IAX2 is possible with
IAXMODEM. So I suppose udptl t.38 should also transparently be passed
between SIP and IAX2. But I find no way to configure t38 on a IAX2

Am I missing something?

-Benoît Panizzon-
I m p r o W a r e   A G    -    Leiter Commerce Kunden

Zurlindenstrasse 29             Tel  +41 61 826 93 00
CH-4133 Pratteln                Fax  +41 61 826 93 01
Schweiz                         Web  http://www.imp.ch

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