The phone number requirement is a problem, but the fact that it's from USA is not. E-mail especially suffers from this.. How about those IM?

• Threema requires paying 3.99 CHF (3.69 EUR, 4.34 USD), but at least you can pay with Bitcoin (but not Monero).
• Wired can't be used with the Tor Browser because it blocks local storage, but maybe you can use Pale Moon with Proxy Privacy Ruler and the domain set to proxy through Tor? You can't pay for the Pro/Enterprise account with a cryptocurrency, but at least a phone number is not required in any case. It also doesn't use Clownflare, but I'm not sure about downtimes.
• Wickr has been acquired by Amazon, so that doesn't sound good... but at least Tor works, I think. I have no idea if you can pay with a cryptocurrency, though, but it's not required. It doesn't have Clownflare and it didn't go down since last 90 days.
• Jami is probably better to use over Tor, considering it's P2P, so your IP could be seen. There's no payment or personal data required. The website doesn't have Clownflare and there's no downtime because it's P2P.

Maybe I'd need to analyze these apps more (including paying for Threema, but who uses it?), but I think Jami would be the best from these.