SMS was designed from the start to fit in the handul of unused bytes in the tower handshake that was happening anyway, hence the 160 char limit. Its marginal cost has always been free on the supply side.

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RF_Savage 5 days ago | parent [-]

SMS routing and billing systems did cost money. Especially billing, as the standards had nothing for it, so it was done by 3rd party software for a very long time.

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margalabargala 5 days ago | parent [-]

Of course, how pleasingly circular. "It's so expensive because it costs so much to charge you for it".

	▲	baq 5 days ago \| parent [-]
		Exactly! AWS is so expensive because it can be so cheap. Billing was the true innovation.