Signal users worldwide can now send and receive crypto payments right through the app, as reported by Wired — actually, according to Signal, it flipped the switch on this all the way back in November, and just never really publicized it. Accessing your wallet is as simple as tapping your profile picture and selecting "Payments." To load up, tap on "Add funds," and the app will give you your crypto wallet address, where you can send MobileCoin.
Like Bitcoin or Ethereum, most cryptos have publicly accessible blockchains where you can look up an address and see both its current balance and incoming/outgoing transactions. MobileCoin, on the other hand, has no such publicly-accessible records and takes steps to defeat tracing, to the point not even Signal knows how much money you have loaded in the app. In this way Signal circumvents the need to identify who purchases what, using what source etc.
Which also means you'll have to buy/sell the cryptocurrency, and it's only available on smaller exchanges like BitFinex and FIX.
See Signal's cryptocurrency P2P payments have quietly gone global
Regulatory scrutiny may still prove problematic in the United States