I am having problems using the mscomm32 api for using modem in visual basic

when i send ATZ to modem and then read the buffer i get this kind of message
:"ATZ#13OK#13"
why does the modem puts the ATZ in the buffer
wait there is more
if i wait for a second , the ATZ goes away and only the OK stays ? What The ****** Fuc** ?

If anyone knows about this usage please reply me

Thank YOu and god bless u all For Helping Me Defuse The Rockets