SIP fax sending software?

Wed May 30 21:32:35 UTC 2018

On 05/30/2018 01:13 PM, John R. Levine wrote:
> Can anyone recommend software that sends faxes over SIP?

No.  Just NO.  The problem is that all the modulation methods that FAX
transmission use requires time stability in the analog channel, and
there is no way that SIP is going to be that stable.

How do I know this?  A number of years ago, a cable system maker asked
me to consult on why V.29 fax wouldn't work over their voice-over-coax
solution.  I used a 23-tone test on the analog channel for 24 hours, and
found the phase jitter was off the charts -- no way that fax machines
could send faxes over the analog channel.  (Traced it to the timing
chain oscillating across the system.)

Have you considered paying the $0.50 per page to have the local copy
shop send the once-a-month faxes?

The other answers have far superior suggestions sending fax over TCP/IP.