I am not sure I agree with the statement that this is not possible. Here is my scenario. We have two space explorers who both set off from Earth at the same time. Their destination is in opposite directions. The travel at the same speed. When they set-off from earth, at that time, a beam of entangled electrons are generated. One particle is transmitted to destination 1, its entangled particle is transmitted to destination 2. This transmission is completed at sub-light speed.
When our two explorers reach their destination and find a beam of electrons constantly arriving. They then try and communicate at superluminal speed. Remember, they have left earth and travelled at the same speed. The atomic clocks they carry will need to be in line. The rules for communication are: -
Traveller A always starts communication.
Communication starts at a fixed time.
Communication ends at a fixed time.
After communication has ended Traveller B starts at a fixed time.
Clearly time needs to be a constant between the two travellers. Difficult, but not impossible to maintain. Any fluctuation in gravity would need to adjust the travellers clock. Anyway, the communication could be done a slow enough speed to enable some time fluctuations.
Traveller A examines an electron. He detects its Spin. This collapses the entanglement and the Traveller B will "see" the spin of the entangled electron (This article indicates that we are able to examine the spin of an individual electron: http://www.sciencedaily.com/releases/2004/08/040811080351.htm).
What the spin is, is irrelevant. It is the gaps in the collapse of the entanglement that will provide the communication.
A simple Morse code effect could then be generated (based on the fixed clocks of the travellers) to enable faster than light communication.
My only grey area is can Traveller B have some apparatus that only reacts when the entanglement is collapsed - e.g. some form of magnetic device that when traveller A collapses the entanglement the other particle then moves to a particular part of the magnetic detector??
I AM NOT A PHYSICIST!!