The cheapest way to fax out of Zoho Creator is not an API at all — it is email. Every mainstream fax provider accepts a message sent to <number>@theirdomain and puts the attachment on the wire. That means Deluge’s built-in sendmail can fax a report template as a PDF with no OAuth, no tokens, and no third-party API to maintain.

Before you start

• An account with an email-to-fax provider, and the sending address whitelisted in their dashboard. Every modern gateway rejects mail from unauthorised senders — this is the step people miss. The address that must be authorised is the one zoho.adminuserid resolves to.
• A form (Procedure_Data here) with Fax_No, Subject_field, Content, and a Fax decision-box field.
• A report template named ConsultPrintFax holding the page you want faxed.

Deluge script

// ── Button action on the report ──────────────
void Send.Fax(int id)
{
    openUrl("#Form:Procedure_Data?recLinkID=" + input.id + "&viewLinkName=Consults_List&Fax=true","popup window");
}

// ── On Edit > On Success of the data form ────
if(input.Fax == true)
{
    // Clear the flag on THIS record only.
    input.Fax = false;

    faxTo = input.Fax_No.replaceAll("[^0-9]","");   // digits only
    if(faxTo.length() == 10)
    {
        faxTo = "1" + faxTo;                        // US/Canada country code
    }

    sendmail
    [
        from : zoho.adminuserid
        to   : faxTo + "@srfax.com"
        subject : input.Subject_field
        message : input.Content
        Attachments : template:ConsultPrintFax as PDF
    ]

    info "Fax queued to " + faxTo;
}

Current gateway address formats

Notes

• Why the flag field exists. The pattern hides every field except the message and fax number, so the user is editing a record purely to send a fax. The Fax decision box is how the On Success script tells “send this” apart from an ordinary edit.
• Set the flag false first. Clearing it before sendmail stops a re-save from faxing twice.
• You get no delivery receipt in Creator. The gateway confirms by email to the sender. If you need status on the record, that is the point to move to a real API such as the RingCentral script in this section.
• Healthcare. Ordinary email-to-fax is not HIPAA-safe. Fax.Plus and Documo offer TLS endpoints under a BAA; use those if the content is PHI.