That is precisely why I am suggesting using a CDN. Old school CDN that is. Back in the day, if you had Akamai, your site would just use one (or many) of their generic names. Nowadays you can use your own domain to front their network, but you don't have to. If Signal was using a few CDN's and cycled through many generic end-point names, then Iran would have to block all the CDN's which would be nearly the same as shutting off the internet. This would not have to be the default mode of Signal. It could be an option that the client suggests. "Hey, it appears we are blocked. Use alternate proxies?" Then cycle through many different CDN's using many generic end-point names. Some of the CDN's can also do layer 4 vips and not have to decrypt anything. They can just act as a TCP tunnel if need be, just costs more.