Session or Briar is honestly a better solution in this case
Discussion
read my other responses about thus
I don't believe session or Briar can be blocked because they use several anonymous relays to connect
Signal doesn't work there?
Iran blocked access to signals servers. The only way they would be able to connect is using a proxy.
Session and Briar are 2 different from Signal messaging applications. Session may be using Signal's encryption protocol, but that does not mean it uses Signal's servers.
And as I know, Signal has implemented a way for iranians to still be able to connect to Signal. It uses proxies, which imo are not that hard connecting to. https://signal.org/blog/run-a-proxy/