Error loading module '' - undefined symbol

Hi everyone,

I have problems to load the res_fax_digium module. I’m using Asterisk 13 (res_fax is already included in this version) on my 64 bit CentOS machine and I want to send and receive faxes using T.38 specification.
So I “purchased” the res_fax_digium (which is actually for free for one channel) module and registered it.
After installation I copied the to the Asterisk modules folder (/usr/lib/asterisk/modules).

But the module isn’t listed in CLI when I type [quote]module show like[/quote] or [quote]config show help[/quote] (so I guess its not loaded)
When I try to load the module file manually via [quote]module load[/quote] CLI prints error

[quote][Nov 17 13:09:25] WARNING[7243]: loader.c:564 load_dynamic_module: Error loading module ‘’: /usr/lib/asterisk/modules/ undefined symbol: ast_format_set
[Nov 17 13:09:25] WARNING[7243]: loader.c:1038 load_resource: Module ‘’ could not be loaded.

Don’t know what I’m missing.
Any suggestions?


There isn’t currently a module for Asterisk 13. For faxing in Asterisk 13, currently, you’ll want to use instead.


Thank you for your response.

Can I send and receive faxes with when I want to use T.38 protocol?


I will have a try and give feedback about the result

edit: thread can be closed. Think res_fax_spandsp is the right thing for me, but with my first configuration tries I ran in some other issues.
Will open a new topic.

Cool :smile: