I know the thread is kinda old but now I know why the iPhone can connect to the internet even with a block. I found out during Rogers' iPhone training last week.
So there are four ports that Rogers has which cellphones use to connect to the internet. For all other phones, except the iPhone, one block is sufficient. Even if they try and block all four ports the iPhone still keeps on trying to connect. Also, they cannot block all four ports, at least one becomes unblocked at some point of time and iPhone can access it (I don't know why it becomes unblocked).
The three blocked ports can prevent the iPhone from accessing the internet through 3G and EDGE but not WiFi. What that means is that if you're using WiFi and are connected to the internet and for some reason the WiFi becomes unavailable for any reason the iPhone will connect to the internet using the 3G or EDGE in spite of the block.
The only way to block it is by jailbreaking it. You can manually turn off EDGE and 3G using SBSettings and that will prevent it from accessing it.
Hope it helps!