This is first of an occasional series looking at mobile messaging technologies. Whilst everyone is smsfamiliar with SMS, there are a number of other messaging solutions, which for various reasons, haven’t had the same global impact the SMS/texting has.

AT&T is in the process of rolling out an emergency alerts update to iPhone users. Its part of a new Commercial Mobile Alert System in the U.S., which allows government agencies to send special text messages to everyone on a particular cell tower. The underlying technology is, however, hardly cutting edge: Cell Broadcast (CB). Officially, SMS-CB, the technology is almost 20 years old.

CB is like SMS, in that recipients get a text message on their phones. But where SMS is like a letter, with the SMSC (short message service centre) acting as a postman making sure the letter goes directly to you, CB is more like a town crier, standing on a street corner yelling. Anyone in earshot hears the message – but the crier has no idea who that is.

So CB is great for doing local messaging. The sender chooses a specific cell, and everyone in proximity gets the message at the same time. The message can hit thousands of devices at once, so long as they’re all in the same geographic area. Obviously, CB used this way is a powerful tool, and there’s great responsibility that comes with it. Whoever uses it will have to use it responsibly, as an extension of the emergency broadcast system. Recent coverage of an amber alert sent in New York perfectly highlights this challenge.

You may be wondering why you’ve never heard of this before. Operators (in general) really struggled to find uses for this technology, especially as the SMS charging model doesn’t work here.

For consumers, challenges include the fact that it reduces your battery life (although that has been significantly minimized over the years), and the ‘on’ switch has been a bit hidden. Almost every GSM phone you’ve had for the last 15 years has supported CB, but I’d bet most people have never even found the menu option.

Notably, the technology didn’t exist in CDMA IS95 – but has been subsequently in to the standards for GSM, CDMA, UMTS (3G) and LTE (4G).

And whilst a few operators had success around advertising—including a couple of operators in the Lebanon in the early 2000s—there have been a few missteps including trying to send content (ringtones) and even in-car maps via cell-broadcast (yes – really!).

So, I’m happy to see that CB has some life in it yet. A general public emergency notification system is really the perfect use case. And devices like the iPhone make it easier for people to find the option on their phones—and use it.

If you’re looking for a great read, here’s a GSMA whitepaper about emergency alerts using cell broadcast.