Is the Azure input endpoint blocked on port 1433?

I am running a Windows Azure working role that provides a WCF service on port 1433, which is also defined as a TCP entry endpoint:

<InputEndpoint name="WcfServiceEndpoint" protocol="tcp" port="1433" />

The same working role also provides another service on TCP port 443, defined similarly:

<InputEndpoint name="TcpInterfaceEndpoint" protocol="tcp" port="443" />

I see both endpoints in the management portal, I can correctly connect to the TcpInterfaceEndpoint on port 443, but I can’t connect to another port at all (I tried SQL servers from two different computers that can access, i.e. the port is not blocked for outgoing connections). When I tried to connect locally to the Azure instance (via Remote Desktop Connection), telnet connected normally. An attempt to connect from other sources ends with a "Connection Timeout". It seems that everything seems like port 1433 is handled differently with port 443 and is blocked somewhere by a firewall. I even tried completely disabling the Windows firewall on the Azure instance, but nothing has changed.

It would seem that Azure does not allow endpoints on port 1433 (this is usually MS SQL Server, we are currently using it due to firewall restrictions in the test environment), but I could not find any information about such restrictions anywhere. So - is that so, or am I somewhere making some kind of trivial mistake?

Added: I tried another test: I switched both ports to the configuration file, so WCF now works on 443 and TCP in 1433. And, as I expected, the WCF service is available, while the TCP interface stops working. Now I am absolutely convinced that 1433 is indeed blocked. It would be nice if this information was documented somewhere.