How HL6528RD send a data to a microcontroller

Hello, everybody

I’m new to HL series. I’m doing a project with HL6528RD and atsam4E. atsam4E is a microcontroller who will send the AT commands to hl6528 par TX/RX. Actually, I use 6528 to send some datas to a server by gprs. If the server receive the message, it will send an answer to hl6528. Now, I want to know, in HL6528, where the answer will be saved, and how can I sned the answer to my MCU?