If your Internet connection blocks access to the Tor network, you may need a bridge relay. Bridge relays (or “bridges” for short) are Tor relays that aren’t listed in the main directory. Since there is no complete public list of them, even if your ISP is filtering connections to all the known Tor relays, they probably won’t be able to block all the bridges.
You can acquire a bridge by sending an email that contains “get bridges” in the body of the email to the following email address: firstname.lastname@example.org
It is also possible to fetch bridges with a web browser at the following url: https://bridges.torproject.org/