martin.swift.is > script > keitai

For more information, see the introduction and analysis below.

Minutes of voice calls per month
Packets of web packets per month

Introduction

When I started shopping around for a mobile phone plan, I found that the SoftBank one's were complicated as hell. There are five main plans (Blue, Orange W, Orange X, Gold and White) and the Blue and Orange ones all have at least five sub-plans — some of which have voice-call rates dependent on the time or carrier called.

So, for anyone wondering which plan is best for the amount of services used, there are a bunch of calculations to be made. And where a bunch of calculations are to be made, they are best handled automatically.

I've set up a PHP script that calculates the cost of each plan based on voice call minutes and finds the cheapest one.

Analysis

Following up on a suggestion made by my brother to present the results graphically, I made the image below. It provides an overview of where each plan is cheapest for a range of voice-call minutes and web-packets.

2D map showing the cheapest prices depending on monthly voice-call minutes and packets downloaded off the web.

a Gnuplot script that made a three dimensional plot of the cost as a function of voice-call minutes and downloaded web-packets.

The following image provides and overview of the cheapest plans. Surprisingly, there are only eight of the fifteen plans included in the calculations show up as cheapest. The calculations excluded those plans with rates depending on time of day or other complications (the white plan was calculated acording to the highest rate).

This is only a first analysis and I hope to improve it soon.

The Gnuplot script that I used to generate the plot.

To-do

This is all in its infancy. On the to-do list are:

Fine Print