fax.rb

require 'phaxio'

Phaxio.api_key = 'xxx'
Phaxio.api_secret = 'xxx'

class Fax
  def send_fax
    file = File.open("/path/to/document.pdf")
    to = 'tel:123-456-7890'
    fax = Phaxio::Fax.create(to: to, file: file)
    response = fax.get
    data = response.instance_variable_get(:@raw_data)
    File.write("fax_#{Time.now.to_i}_response.txt", data)
  end

  def fax_status(fax_id)
    fax = Phaxio::Fax.get(fax_id)
    puts fax.inspect
  end
end

Fax.new.send_fax