I would bet my bottom dollar that Sec Def, Sec State, and CIA director have never planned strikes in a Signal groupchat in any prior administration, including Trump 1.

What about over a PSTN?

Probably. https://en.wikipedia.org/wiki/STU-III

I'm a little surprised that encrypted voice fits through PSTN. like, logically voice can fit, and encryption shouldn't change message size, but plaintext (plainspeech?) voice over PSTN is/was analog, while the ciphertext is digital. I wonder if the quality suffered.

I honestly wouldn’t know but I also wouldn’t be surprised if they did. DC lives in its own universe with its own rules.

Note this is your opinion only.

There has never been any reporting that previous administrations have discussed war plans over a non US government platform before.

That's... not what they said.

They did say that “really sensitive stuff” was being shared on Signal.

Which really only includes things like war plans.