Is there a fax service on the web which I can use with "sendfax" command line client?

Hello,

do you know if a fax service exist on the web, which I can use with
Hylafax' "sendfax" command line client?
I looked at www.ringcentral.com and www.myfax.com but they do not support
"sendfax" client.

I'd like to replace our in-house Hylafax fax server with a similar fax
service on the web, but I do not want to make too much changes in the
application sending faxes via "sendfax" client!

Thank you fro your ideas and help!