GPRS Shield - How to answer an incomming call or SMS?

Products & Technology Shields
2

For the Calling income number,you can set “AT+CLIP=1” then it will show the income call number.
you can search the AT command in the datasheet by find “CLIP”.

For the SMS,you can use the AT+CMGR,you also can check it into the datasheet.
SIM900ATCommand:http://garden.seeedstudio.com/images/a/a0/SIM900_ATC_V1_00.pdf