Just because the code shows blocks of four digits does not mean that each block represents one word. This is simply the format of the mesage.
Niether would one digit necessarily represent one Chinese character or a letter of an alphabet (English for example).
In fact the Chinese often used one digit to represent one (Chinese) spoken 'sylable'.
Going back to the groups of digits one needs to also look within each group and across groups to find repetitions to aid with the dicipherment.