Why in a world when data transmission prices are falling does it cost so much for an SMS message, which is just pure data? Did you know sending an amount of data that would cost $1 from your home ISP would cost over $61 million if you were to send it over SMS? This article looks at the real cost of an SMS message.

A standard SMS message contains up to 140 bytes (1120 bits) of data - this takes care of the 160 characters allowed in your text message. This might not make sense at first, until you realize that SMS uses 7 - not 8 - bit characters - leaving you with 128 possible character values instead of the normal 256. So 1120bits/7bits = 160 characters.

So our total message length is about a tenth of a kilobyte (.13671875 Kbytes). In terms that the iPod generation would understand - if you had an iPod with a tenth of a kilobyte you could fit 1/4000th of a song on it. I assume here and for the rest of this article that 1 song = 4 Megabytes.

If you divide 140 (the total number of bytes available to you) by 20 (the cost per message), you find that you are paying 1 cent for every 7 bytes of data. This leaves you with a cost of $1,497.97 for the 1024Kbytes contained in a single megabyte. iPod users: It would cost you $5,991.88 to transfer - not even to buy - a single song via SMS. [...]

I know the true cost of SMS messages!

I made a paper for the univeristy some years ago. The marginal cost of a SMS is 0.

They do have a little cost/opportunity. As a matter of fact SMS messages are sent on the control channel. Initially SMS were implemented in the GSM standard as a control system, just like the ICMP protocol of the IP stack. Then NOKIA though to implement a actual instant message function using SMS. The Contol channel is the channel that your mobile listens to in order to receive calls. So for receiving a SMS a control signal is sent. Since bandwidht is somehow limited on these channels it could happen that in a situation of massive usage of texting the control channel gets saturated and normal voice protocol initiation is disrupted. To prevent this carriers nowadays apply a kind of QoS delaying SMSs until there is no risk of congestion. So we can state that the marginal cost is 0 and the cost/opportunity is also 0

Another story is for the MMSs. Their cost/opportunity is even lower since they run almost enterely on GPRS thus using most bandwidht on normal data channels. Thus a MMS with pictures sounds and maybe video SHOULD cost less than a SMS.

So you wonder, why do I pay so much for a SMS or a MMS or even a Call: after the debts for the initial hardware infrastructure have been paid by the carrier you are still paying because of market segmentation (You won’t change the carrier on the fly) and a little monopoly (Almost impossible to start a new carrier from 0).

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