Maybe in theory. The message I get from almost everyone at a regulated institution is Bloomberg, e-mail, or voice. When the SEC is on a warpath, compliance and legal departments don’t play with anything but the clearest black and white lines to optimize for the convenience of staff. It is frustrating because it imposes a monopoly tax on financial market participants to get a Bloomberg or be shut out of information flow which is death in markets. I’ve yet to find anyone I deal with who says hey find me on Symphony.
https://symphony.com/
but also whatsapp and imessage from company-owned devices. The fines were about chat communications from personal devices.