twilio_pricing.rb

class TwilioPricing
  attr_reader :pricelist
  
  def initialize
    self.refresh_pricelist
  end
  
  def pricing_for(number, duration = 1)
    internal_number = number.to_s.scan(/\d/).join('') # cast and filter...
    if number.length == 10
      # I'm going to prefix this with a '1' because it's *probably* North American.
      internal_number = '1' + internal_number
    end
    key = nil
    internal_number.length.times {|time|
      hit = @pricelist[internal_number[0..time]]
      key = hit if hit
    }
    if key
      key[:duration] = duration
      key[:total_rate] = (key[:rate].to_f * duration.to_i).to_s
    end
    key
  end
  
  def refresh_pricelist
    pricelist = {}
    rates = open('http://www.twilio.com/resources/rates/international-rates.csv')
    rates.lines.each {|line|
      sections = line.split(',')
      prefixes = sections[2].split(' ')
      prefixes.each{|prefix|
        pricelist[prefix] = {
          :country => sections[0],
          :rate => sections[1]
        }
      }
    }
    rates.close!
    @pricelist = pricelist
  end
end

The hash that pricing_for returns has the same key/value pairs as you'll find from the app at http://twilio-rates.appspot.com/

The only difference is that you don't have a 'status' key - if things go wrong or your number isn't found, you'll get nil back.