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.
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.