WIthin your AT command pdf page 44 of !PCOFFEN it says:
The modem can be configured to enter low power mode or power off when W_DISABLE is asserted. (This is called the Power Off Enable feature.)
Does this mean the MC7455 can literally be turned off with a W_DISABLE assertion or is this just another way of saying it will still go into Low Power mode like what happens when using at+cfun=0