Item response model in Stata 12

Dear all,

I would like to use item response model (that is developed with Stata version 14) in Stata 12.

However, whenever I tried to install it via "ssc install itr" or " findit itr" I could not find it.

Is it not possible to use item response model with Stata 12?

P.S: the command for the item response model is
irt grm

Thank you,
Maya