For 14 years I've been using RingCentral's email<>FAX gateway with
success. It used to cost about $10/month if paid annually, but
they've raised that considerably since (I'm grandfathered on the cost).

Once subscribed, you can email many common document types as a file
attachment to <faxnumber>@rcfax.com and they render it as a fax to
the destination fax machine. Then a few minutes later they email you
a confirmation that it was successfully received (or not.) Inbound
faxes to your RingCentral fax number arrive as PDF's to your email
inbox. It works pretty well.

Years ago I setup an enterprise client with a similar service called Faxmail.com but they seem to have been bought out by a less friendly
provider. Some email<>FAX gateway providers (like eFax,
IIRC) require you to use their proprietary software and seem to
monetize your traffic.

I often use RingCentral FAX to exchange faxes containing patient
medical info with medical service providers for myself and family
members. I think HIPAA prohibits emailing such info, so most doctors
seem to have a fax machine (or some kind of fax service) for
compliance reasons. Ironically, because email<>FAX gateways use
email as part of the path, using one for exchanging patient medical
info probably violates HIPAA.

FAX over VoIP -- can be done successfully depending on the CODEC
that the VoIP provider uses. I recently discovered a FAX-friendly
feature of Ooma is to prefix the outgoing fax call with *99 which
invokes a FSK-friendly CODEC. I'm not sure if/how Ooma can be used
to successfully receive faxes. Contacting your VoIP provider(s)
higher-level tech support staff might yield useful info, such as any
dialed prefix with invokes a FSK-friendly CODEC for that outbound
call. I had to talk with several Tier III tech support staffers at
Ooma to reach a someone who knowledgeable about this.

I don't think there's any legal requirement that VoIP providers such
as Callcentric support such a capability. But obviously, the slower
the fax/modem connection speed (bits per second) the more reliable
the transmission will be. Some older Group III fax machines have
modems that can negotiate all the way down to 300 bps, which would
wonk better over some VoIP connections. YMMV.

-bernieS

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