> Servers: $2.9 million dollars per year.
> Registration Fees: $6 million dollars per year.
> Total Bandwidth: $2.8 million dollars per year.
> Additional Services: $700,000 dollars per year.
Signal pays more for delivering verification SMS during sign-up, than for all other infrastructure (except traffic) combined. Wow, that sounds excessive.
Moving off cloud services to lower-cost provider like Hetzner, Vultr and DigitalOcean might provide a lot of cost savings.
I also imagine they're using managed SMS services from one of these clouds, and moving off them to a combination of local SMS gateways in each country can also further reduce costs (and in one case I've personally observed, by upto two orders of magnitude). This obviously pushes a lot of complexity on Signal's side, but is usually worth it.