[vader1]

In many countries it's not (legally) possible to buy a SIM card without providing your ID.

Sure, you go ahead and buy an illegal burner number, then download Signal/Whatsapp from the Play Store and reverse engineer that binary to see if it "does what it says". Other people might find it useful to look at this comparison to discover alternatives that better fit the characteristics they find important.

[lvh]

I know; I lived in one. A burner number does not imply getting a SIM. That is not how journos in sensitive countries get a number.