Why SIM100T don't support the command AT+CPMS = "SR&quo

at+cpms=sr

Hi,
I have a GSM modem. my GSM modem's model is SIM100T.
I am using AT commands for communicataion by GSM modem.
I want to get delivery reports from GSM modem.
I am recieving the below answer from SGM modem :

+CDS: 25
062...

and I know this answer is for delivery report.
BUT I want to use the memory of GSM modem and get the delivery reports that be stored in it.
for this , I have to use the below command :

AT+CPMS="SR"

This command allows the message storage area to be selected ( for reading, writing, etc ) and "SR" is Status Report message storage.
My modem only work with AT+CPMS="SM" and don't work with AT+CPMS="SR" or AT+CPMS="BM" or etc.

When I use the command AT+CPMS="SR", then the modem's answer is ERROR.

I want to know do my GSM modem support it or don't ?
Thanks alot.

O.R.B