I've been in this game long enough to remember when "Tier III" meant something because only five companies in Europe could claim it. Now it's on VPS plans that cost 4 euros. The devaluation is complete.
Tier III on the wall vs Tier III in reality
Contabo doesn't claim Tier III, to their credit. They just say "German quality data centers" which means nothing but also claims nothing. I'd rather that than a lie.
This thread made me check my provider. They have a "Tier III design" cert from 2018 on their about page. I emailed for the number. No response in 72 hours. That IS the response.
So what's the consensus? Ask for the cert number, verify it, and if they hedge, treat it as unverified? Is there a list somewhere of providers that actually hold current operational certs?
Uptime Institute publishes a directory but it's incomplete, lots of holders don't opt in. The only reliable method is direct verification. My working rule: if they won't give me a cert number in one business day, I assume they're unverified. Saved me from two bad contracts.