Jesus, that sucks. Do they also block VPNs, say on ports 80 and 443? Some VPNs use SSH and/or SSL (stunnel) for obfuscation. iVPN uses obfsproxy. A few use OpenVPN hacks, or proprietary obfuscation.
As far as I can tell, no. But their home broadband division is a spectacular mess of four quasi-autonomous networks acquired through mergers and buyouts, so your mileage may vary depending on which block you land upon.
After all, it is really a lazy way to save transit costs by making sure that domain names resolve to a CDN they have peered with, or in the worst case, to a transparent HTTP caching proxy they have set up.
Good reason to use a VPN, I guess.