Iax trunk or sip trunk?

General Help
1

hi ,
i want to send fax by hylafax client , i have sip trunk with provider , i want to send to to fax by trunk from provider.

the question is :
for fax

do i need iax trunk ??
or sip trunk ??

or whatever will work ???
with to help

regards

2

I’ve used both IAX2 and SIP trunks for faxing but make sure that you stick with G.711a or G.711u throughout. Transcoding has a very bad effect of fax signalling.

FAX can be unreliable over IP anyway but I’ve personally not had major problems using modern fax machines or fax to e-mail.