The principle is simple: in various parts of the financial sector, there is a requirement that communications about transactions must be conducted through a medium that provides a record of the correspondence or communication.
Across the whole world, it's a long-standing requirement especially in securities businesses.
But there's a problem. Or rather there are many problems.
Let's look at the most basic of all: traders are in the risk business. In fact, personality tests show that they are fundamentally similar to criminals. It's either their morality or the risk of getting caught that keeps them on the right side of the law. Ish. While the vast majority stop short of out and out dishonesty, stealing customers' money for example, there is a much bigger problem with, for example, insider trading.
In fact, it's insider trading rather than fraud or even to ensure that there is a record of trades that drove the creation of rules that all communications relating to business must be recorded either in audio or in a text format.
But no one seriously believed that that was workable unless the trader was sitting at his desk using his office terminal or his desk phone. But as that was where traders worked, it was kind of ok.
But the trouble is that wasn't where traders worked. Even before CoVid-19 drove everyone to work from home, people were using all kinds of tech to free themselves. They weren't doing it to evade the controls, they were doing it because in a 24 hour trading world, no one can be at their desk twenty-four hours a day, 365 days a year and there's an imperative to go home, take the family out and even spend a few days working from the deck of a yacht or a beach in Bali. And that means using tech that isn't in the office.
There is also a cultural issue: when the rules were formed, mobile phones were still relatively primitive and messaging apps were a novelty. But now they are the first thing people think of when they want to talk or write to someone. And the reality is that most people who want to make a quick phone call don't stop to think "is this authorised?"
Don't imagine that there aren't people who use WhatsApp, Telegram or Signal or, previously, Blackberry because they think they are private and they can do dodgy business without being found out. Of course there are. But these are the same people who would write a tip on a Post-It and tack it to the underside of a table in a bar to be picked up unobtrusively.