Why are we charged R4850 / $643 / £387 per megabyte for Text Message (SMS) services?

09 Nov 2009

How Text Messages work

With 35% of all mobile phone users worldwide being active text messaging users (as of 2003), it is the most widely used mobile data service on the planet (according to Wikipedia).

When a text message is sent, it travels wirelessly from a mobile handset to the closest available cellphone tower. From there it's transferred via wired connections to the destination tower, then transmitted wirelessly from the destination tower to another mobile handset. Text messages (being only 160 characters in length) are so small that the costs associated with the use of the radio spectrum as well as the wired connections should be infinitesimal.

Additionally, text messages don't use a dedicated channel while being transmitted to cellphone towers. Instead, they piggyback on the "control channel", a range that's reserved for initiating phone calls and other handset-to-tower and tower-to-handset communication (the use of this channel is why text messages have a length limit: 160 characters is the maximum size of a "control message").

This channel is always open and always active between handsets and towers; when mobile devices send text messages they're simply slotted into any openings available.

Calculating the real cost of a Text Message

A text message can be up to 160 characters (the actual size of messages transmitted over cellphone towers' control channels are 140 bytes – 160 7-bit characters), and 160 characters equal 160 bytes, one byte per character.

In computer science, the common-use values of bytes, kilobytes, megabytes, gigabytes and terabytes are calculated as follows:

1024 bytes = 1 kilobyte (kibibyte) (KB)
1024 kilobytes = 1 megabyte (mebibyte) (MB)
1024 megabytes = 1 gigabyte (gibibyte) (GB)
1024 gigabytes = 1 terabyte (tebibyte) (TB)

To calculate how much an SMS costs in terms of megabytes, you need to divide a single full-length message's cost by 160 to get the cost per byte, multiply the answer by 1024 to get the cost per kilobyte, and multiply it by 1024 again to get the cost per megabyte.

So, assuming that a message is exactly 160 characters long and the carrier charges R0.74 for it (South African Rands, a rough average of the cost on the South African cellphone networks):

R0.74 / 160 = R0.004625 per byte
R0.004625 * 1024 = R4.736 per kilobyte
R4.736 * 1024 = ~ R4850 per megabyte

Paying R4850 per megabyte for any kind of data, even in South Africa with its horrible bandwidth costs, is ludicrous.

Putting Text Message costs in perspective

To put this R4850 in perspective, the table below compares the cost of local ADSL bandwidth per megabyte against the cost of text messages per megabyte (all costs are accurate as of the writing of this post, calculations are rounded to four decimals):

Provider	Service Name	Cost per Gb	Cost per Mb	Versus Text Message
Axxess	DSL Topup	R69	~ R0.0674	x 71958.4570 cheaper
Mweb	1 Gig Booster	R66	~ R0.0645	x 75193.7984 cheaper
Telkom	DSL TopUp	R65	~ R0.0635	x 76377.9528 cheaper
Web Africa	Prepaid	R70	~ R0.0684	x 70906.4327 cheaper

Why are we being overcharged an average of 73609 times the fair data cost for text messages?

Dr Nigel Banister, a scientist at the University of Leicester, compared the cost of sending a text message against that of downloading data from the Hubble Space Telescope (a 11,110kg satellite that cost several billion dollars and was designed to orbit 559km above the surface of the earth). Using his "most pessimistic" estimate for the telescope's transmission costs (£85 a megabyte), he found that a text message can cost up to 4 times more than downloading the same amount of data from the telescope would.

Let's assume the average song in the iTunes Store is 4MB in size, the average TV Series episode is 500MB, and the average movie is 1GB.

Using text message bandwidth rates, the costs involved in getting your media from the iTunes Store would amount to:

Media	Purchase Cost	Download Cost/th>
Song	$0.99 R7.47 £0.60	$2,570.00 R19,400.00 £1,548.00
TV Series Episode	$2.99 R22.57 £1.80	$321,276.00 R2,425,000.00 £193,528.00
Movie	$9.99 R75.40 £6.02	$657,974.00 R4,966,400.00 £396,346.00

Absolutely ridiculous!

Comparison of Text Message costs across networks

Below are comparisons of some countries and their network providers, as well as how much they're charging per megabyte for text messages on contracts:

Network & Contract	Peak	Off-Peak	International	Peak Cost per Mb
America AT&T	$0.20 ~ R1.51 ~ £0.12	-	$0.25 ~ R1.89 ~ £0.15	$1310.72 ~ R9,893.35 ~ £789.54
America Verizon	$0.10 ~ R0.75 ~ £0.06	-	$0.25 ~ R1.89 ~ £0.15	$655.36 ~ R4,946.67 ~ £394.77
South Africa Cell C	~ $0.11 R0.80 ~ £0.06	~ $0.05 R0.36 ~ £0.03	-	~ $694.60 R5,242.88 ~ £418.41
South Africa MTN	~ $0.10 R0.75 ~ £0.06	~ $0.10 R0.75 ~ £0.06	~ $0.21 R1.60 ~ £0.13	~ $651.19 R4915.20 ~ £392.26
South Africa Virgin Mobile	~ $0.08 R0.60 ~ £0.05	~ $0x.08 R0.60 ~ £0.05	~ $0.16 R1.20 ~ £0.10	~ $520.95 R3932.16 ~ £313.81
South Africa Vodacom	~ $0.11 R0.80 ~ £0.06	~ $0.05 R0.35 ~ £0.03	~ $0.23 R1.74 ~ £0.14	~ $694.60 R5,242.88 ~ £418.41
United Kingdom Orange	~ $0.20 ~ R1.50 £0.12	-	-	~ $1,305.55 ~ R9,854.34 £786.43
United Kingdom Vodafone	~ $0.20 ~ R1.50 £0.12	-	-	~ $1,305.55 ~ R9,854.34 £786.43