Doesn't look like very sophisticated blocking, on MTS at least they seem to intercept DNS traffic and respond to www.bbc.com wtih their own
If you ignore the certificate warning you get a redirect to http://blocked.mts.ru/?host=www.bbc.com
Which states (in Russian):
Access to the information resource is limited on the basis of the Federal Law of July 27, 2006 N 149-FZ "On Information, Information Technologies and Information Protection
If you override the DNS entry, it loads fine, at least for me on my MTS circuit.