[asterisk-users] IAXModem or T38Modem?

Karsten Wemheuer kwem at gmx.de
Mon Mar 24 06:44:59 CDT 2014

Hi Mike,

Am Montag, den 24.03.2014, 01:41 -0400 schrieb Mike Diehl:
> Hi all,
> I'm installing Hylafax on my Asterisk system.  From what I've read, I
> can either use IAXModem or T38Modem to provide the virtual fax device.
> So at the risk of starting a religious war, which one should I use?
> I don't mind running IAX if I have to.  I want as much flexibility and
> stability as I can get.
> So, what are your recommendations?

It depends on Your environment and Your asterisk version. If Your
connection to the PSTN is via ISDN (eg. channel via DAHDI or CAPI), You
should use IAXmodem. The fax is transferred on the audio layer and there
is no need to translate it into T.38. If Your connection is via some
VoIP Provider using T.38 or via a Mediagateway like BeroFix, You should
use T38Modem.

Newer versions of asterisk have additional features regarding T.38
(AFAIK). In this case there may be no need for any of the modems.



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