Where are the fax instructions?

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Asterisk Users 6 Comments

Hello,

Trying to set up res_fax_spandsp. Based on
https://wiki.asterisk.org/wiki/display/AST/T.38+Fax+Gateway I wrote this in
my extensions.conf:

exten => 306,1,NoOp(Fax transmission)
same => n,Set(FAXOPT(gateway)=yes)
same => n,Dial(DAHDI/3) —–>FXS port to fax machine
same => n,Hangup()

Call flow Im trying to pull out is as follows:

Zoiper –> Asterisk with TDM410 –> FXS –> Analog fax machine

I am totally lost about the use of this new gateway module in the dialplan.
I think it loads ok:

CLI> fax show capabilities

Registered FAX Technology Modules:

Type : Spandsp
Description : Spandsp FAX Driver
Capabilities : SEND RECEIVE T.38 G.711

1 registered modules

Also I have the FFA manual, which I couldn’t understand. I think FAXOPT is
common to both, but still not sure how to put them together. Where can I
find documentation about configuring the call flow described?

Or some insight will also be appreciated.

Here is my sip peer config:

[105](headquarters) ;zoiper phone
type=friend
secret=
mailbox=105@default
t38pt_udptl = yes

Dahdi:
;FXS Modules
group = 2
signalling = fxo_ks
context = interno
channel = 3-4
faxdetect = both

Finally, a verbose output:

== Using SIP RTP CoS mark 5

6 thoughts on - Where are the fax instructions?

  • Your res_fax_spandsp module was built without gateway support; what
    version of Asterisk are you using?

    Fax for Asterisk is totally unrelated to T.38 gateway support.

    Since ‘fax show capabilities’ did not show that you have gateway
    support, you won’t be able to enable it. That problem must be corrected
    first.

  • Thanks from the bottom of my heart sir!

    Asterisk 1.8.7.1 is my build, I couldn’t chose res_fax_spandsp from
    menuselect due to dependencies, so I installed libspandsp-dev:

    :~# apt-cache policy libspandsp*
    libspandsp2:
    Installed: 0.0.6~pre12-1
    Candidate: 0.0.6~pre12-1
    Version table:
    *** 0.0.6~pre12-1 0

    libspandsp-dev:
    Installed: 0.0.6~pre12-1
    Candidate: 0.0.6~pre12-1
    Version table:
    *** 0.0.6~pre12-1 0

    So, my dialplan snippet looks good, but I need to correct the lacking
    gateway capability?

    *José Pablo Méndez
    *********

  • Kevin,

    I rolled back clean my virtual asterisk testbed and instead of libspandsp2
    and libspandsp-dev, I installed libtiff4 – libtiff4-dev and
    downloaded/compiled spandsp 0.0.6, then I fixed the libraries with

    echo “/usr/local/lib” > /etc/ld.so.conf.d/spandsp.conf

    cuz it wasn’t able to load the module at all. Now it does but still can’t
    see any reference to gateway support.

    Installed Asterisk 10 package, ./configure proves good spandsp support:

    checking for minimum version of SpanDSP… yes
    checking for span_set_message_handler in -lspandsp… yes
    checking spandsp.h usability… yes
    checking spandsp.h presence… yes
    checking for spandsp.h… yes
    checking for t38_terminal_init in -lspandsp… yes
    checking for spandsp.h… (cached) yes

    I decided to give 10.0 a try since res_fax_spandsp is included in the
    native code right? (if that even has any sense). It now shows:

    CLI> fax show capabilities

    Registered FAX Technology Modules:

    Type : Spandsp
    Description : Spandsp FAX Driver
    Capabilities : SEND RECEIVE T.38 G.711 GATEWAY

    1 registered modules

    I would consider this one solved but could you please throw some insight as
    to why 1.8.8.0 and 1.8.7.1 fail to build the gateway support?

    Thanks again,

    *José Pablo Méndez
    *********

  • res_fax_spandsp exists in Asterisk 1.8, and provides FAX termination and
    origination services (for both T.38 and T.30 FAXes). In Asterisk 10, it
    gained T.38 gateway support.