SIM900 SMS and Call Commands

The CALL READY message from the SIM900 indicates that the modem is powered up and has acquired a valid network. Next thing is to make sure you have set the SIM900 into TEXT mode by sending the command AT+CMGF=1; followed by a carriage return(rn).

If you are facing any problem with respect to modem not responding to commands read my previous article to solve it.. it applies to SIM900 problems too. 

Reading a SMS message from the Inbox:

• To read the first SMS from the inbox send the command AT+CMGR=1 followed by rn. The modem will reply with the text of the first SMS in the inbox along with senders mobile number and date and time.

• To read the second SMS from the inbox send the command AT+CMGR=2 followed by rn. The modem will reply with the text of the second SMS in the inbox along with senders mobile number and date and time.

… and so on. The maximum number of SMS messages in the inbox depends on the SIMCARD you have put in the modem.

• To read all the SMS messages from the inbox send the command AT+CMGL=ALL followed by rn.  The modem will reply with the text, senders number, timestamp of the all the messages in the inbox in one shot. 

Sending SMS message from SIM900:

• To send SMS from SIM900 send the command AT+CMGS=9900243245 followed by /r/n and then the message text and then the ascii code of Ctrl^Z character which is 0x1A

ex: To send “Hello” to 9900243245 mobile number

AT+CMGS=9900243245 followed by rn 

Hello

Ctrl^Z ascii code 0x1A followed by rn (Ascii code for n is 0x0A and Ascii code for r is 0x0D)

Deleting a SMS message from the Inbox:

• To delete the first message from the inbox send the command AT+CMGD=1 followed by rn. The modem will delete the first message in the inbox.

• To delete the second message from the inbox send the command AT+CMGD=2 followed by rn. The modem will delete the second message in the inbox.

… and so on. The maximum number of messages in the inbox depends on the SIMCARD you have put in the modem.

Calling to a number using SIM900:

• To call to a number send the command ATD followed by the mobile number and carriage return ,

To call the mobile number 9900243245 send the command as,

ATD9900243245 rn

Hanging up a call in SIM900:

• To hang up a ringing call or a call in progress send the command ATH; followed by carriage return

ATHrn

Recieving a call in SIM900:

• To receive a ringing call, Send the command ATA; followed by carriage return

ATArn

Finding the number of the incoming call in SIM900:

• To get the number of the incoming call you need to enable the Caller Line Identification in SIM900.
• To enable the incoming caller line identification issue the command AT+CLIP=1 followed by carriage return

AT+CLIP=1rn  

Once you issue this command, any incoming call will be notified in the following format,

RING

+CLIP:+9916258273

Here +9916259273 is the number of the incoming call. 

Click on below Image to Watch the video for Live demonstration of the above commands: