Is IAXModem Supports T1 Lines or ISDN PRI?


I’m trying to figuring out that whether IAXmodem supports either T1 (voice channels) or ISDN PRI? Because currently I’m trying to use T1 (voice channels) for communicating with Fax modem devices.

If any person knows this information please do share it.

IAXModem takes away the need for a DSP card. With it you would not need to buy say a Dialogic board.
You create multiple IAXModem channels which each would handle one fax connection.
Using Asterisk you bridge from your input to the IAXModems.

A co-worker of mine has used it. We take the incoming calls from our PRI, then route them to the IAXModem. Which is configured with Hylafax for fax reception.

exten => 5591,1,Macro(DialIAXFax)

exten => s,1,Dial(IAX2/to-fax0/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax1/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax2/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax3/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax4/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax5/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax6/${MACRO_EXTEN},15)
exten => s,n,Dial(IAX2/to-fax7/${MACRO_EXTEN},15)
exten => s,n,Noop(Status=${DIALSTATUS})
exten => s,n,Busy(15)
exten => s,n,Hangup


Thanks for your feedback but my question remains the same that either IAXmodem supports PRI(ISDN) or T1/E1 (voice lines) only?

Please do let me know about it.

I believe the answer is neither.

IAXModem is software modem that uses an IAX channel.

You need to bridge the IAX channel to some other channel. If you have a T1, ISDN PRI, or analog phone lines communicating with your asterisk box, then you should be able to bridge the two channels together to make a link.

Can you give me some sample configuration because my flow is listed down below;

User => Hylafax (through email2fax or virtual fax printer) => iaxmodem => asterisk => T1 => PSTN [AND Vise Versa]

As using this flow how can I bridge iax channel? Please do assist me on this point.

I’m not familiar with iaxmodem, but I don’t see why this requires any special handling in Asterisk, other than ensuring that a sensible codec is used. What happens when you try and configure it as a standard, IAX, extension?

The reason I want to use Iaxmodem, because after testing asterisk + fax, my goal is to use pager with asterisk. Where iaxmodem is a soft modem and by which it may communicate with asterisk and paging devices. If you know the way for integrating / communicating pager (TAP) with asterisk, please do let me know about it.

Please read the book at and read and generally understand configs/extensions.conf.samples.

I’m surprised that TAP is still available; it pretty much died out in favour of internet options about a decade ago in the UK.

I’m confused by your one minute talking about fax and the next about TAP!

The reason of using hylafax + iaxmodem is because hylafax also supports paging (TAP) as well. If I figure a way out to send and receive fax using hylafax+ iaxmodem + asterisk, then I’ll able to use pager as well, because hylafax does also support pager(TAP). So kindly assist me on this problem that how can I send fax messages over T1 and even I follow this document but still unable to send it. The document which I was following is listed down below; … on-hylafax

Kindly help me out this matter for sending fax over T1 lines (using asterisk box)

You haven’t stated what you have done. How would we know for what to provide assistance?

Which version of asterisk are you running? did you compile from source or a package? Which distro are you running?

Following the directions on the page you provided, I installed iaxmodem 1.2.0 on my asterisk box. Which is running centos 5.5 and Asterisk I then was able to
echo atdt3000 > /dev/ttyIAX0
This caused the iaxmodem to handle the ATDT command. Asterisk saw it and my dialplan told it
exten => _X.,1,Dial(SIP/${EXTEN})

so by changing the echo line I rang different SIP phones.

I did not worry about the hylafax part as its not necessary for this test.