Signal Messenger has recently been blocked in Iran along with various internet restricting measures being implemented there. In a blog post on their official site, Signal encouraged community members to run a Signal proxy to circumvent the censorship.
We have deployed our own Signal proxy at https://signal.tube/#signal.zcyph.cc to help Iranians in need.
To use it, simply open the URL from any mobile device with Signal installed, and then select Use proxy.