I am a developer in a big company that acts as SMSC. We work with hundreds of operators around the world. The explanation in the article is way better that all

I am a developer in a big company that acts as SMSC. We work with hundreds of operators around the world. The explanation in the article is way better that all internal documentation combined we have in the company. I wrote algorithms to convert 8bit to 7bit and back as some our customers require that. One thing that strikes me about SMS is that most people think SMS is secure and offer great privacy. It is not. The messages are not encrypted, and from the technical perspective there is no way to prevent SMSC from reading your messages.