4 ms·

I think you are mixing that up: SMS uses a signaling channel of GSM. It was originally not intended to become that big and just used otherwise unused resources.

I think you are mixing that up: SMS uses a signaling channel of GSM. It was originally not intended to become that big and just used otherwise unused resources. Therefore it could have been given out for free or very cheap. Later on telecom providers saw that people like text messages and that it has an enormous business potential, so they started to make huge charges for it.

TorKlingberg 10y ago
The "otherwise unused" isn't true. Any time your phone is transmitting, it is using some of available bandwidth in the air. It does go other the control channel is GSM rather than setting up a data channel, and is was originally just for testing, carrier announcements etc. The per-SMS charge is far higher than actual costs, but so is everything. Mobile networks are almost entirely fixed costs in building the network.