GSM

GSM (Global System for Mobile Communications, originally Group Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones.

AT command set for GSM Mobile Equipment

Adapted from

http://www.etsi.org/deliver/etsi_gts/07/0707/05.00.00_60/gsmts_0707v050000p.pdf (GSM 07.07 Version 5.0.0)
http://www.etsi.org/deliver/etsi_ts/127000_127099/127005/04.01.00_60/ts_127005v040100p.pdf (3GPP TS 27.005 Version 4.1.0 Release 4)

Command	Purpose
ATZ	Sets all parameters to their defaults
ATI	Requests manufacturer specific information
AT+GMI	Requests manufacturer identification
AT+GMM	Requests model identification
AT+GMR	Requests revision identification
AT+GSN	Requests serial number
AT+CPIN	Enter PIN
AT+CMGF	Message format to use
AT+CMGL	List messages
AT+CMGD	Delete message
AT+CLAC	List of supported AT commands
AT+CSQ	Signal strength
AT+COPS?	Current network operator

SMS PDU Encode Decode

http://twit88.com/home/utility/sms-pdu-encode-decode

Send SMS text mode

picocom -b 9600 /dev/ttyUSB0
atz
ati
at+cmgf=1
at+cmgs="960000000"<enter>
testSMS<ctrl+z>

Set GSM number in SIM card

at+cpbs="ON"
at+cpbw=1,"911234567",129,"GSM number"
at+cnum #check number

Set SMS message center

at+csca="+351911616161",145 #Vodafone Portugal
at+csca="+351962100000",145 #TMN
at+csca? # check SMS message center

AT+CSQ signal strength

Value	RSSI dBm	Condition
2	-109	Marginal
3	-107	Marginal
4	-105	Marginal
5	-103	Marginal
6	-101	Marginal
7	-99	Marginal
8	-97	Marginal
9	-95	Marginal
10	-93	OK
11	-91	OK
12	-89	OK
13	-87	OK
14	-85	OK
15	-83	Good
16	-81	Good
17	-79	Good
18	-77	Good
19	-75	Good
20	-73	Excellent
21	-71	Excellent
22	-69	Excellent
23	-67	Excellent
24	-65	Excellent
25	-63	Excellent
26	-61	Excellent
27	-59	Excellent
28	-57	Excellent
29	-55	Excellent
30	-53	Excellent