SMS message received indication

I’m working with the Nova and am running is serial mode. I can receive SMS’s , ( a +CMGL shows the new SMS) but I can’t seem to figure out how to know if one had landed. I set the radio with the +CIMI, , +CIMI: The +UMWI yields zeros, yet if I list the messages, there they are. I’m sure I’m not setting something correct, but I don’t know what.