1. The Short Message Service Centre SMSC ME MAST SMSC LOCAL MOBILE NET

2. The Short Message Service (SMS) The SMS service uses part of the bandwidth capacity of the existing 2G voice network. It was originally intended for use by the mobile phone companies to contact their operatives in the field undertaking maintainance work The SMSC relays SMS messages from a Mobile Equipment (ME) to another ME The SMS is sent to the nearest call mast, forwarded to the SMSC. The SMSC stores the SMS and then attempts to deliver it to the destination ME. After a preset period of time, known as the Validity Period, the message is deleted from the SMSC if it cannot be delivered. The SMS can also be forward on to a computer or logical ME is the mobile network's LAN.

3. INTRODUCTION TO DATA OVER GSM ANALOGUE – e.g V22 etc SHORT MESSAGE SERVICE – SMS GPRS BASIC SMS COMMANDS AT+CMGS=”+447967123456” > ENTER TEXT CONTROL Z AT+CMGR=NN AT+CMGD=NN AT+CMGW=”+44796123456” > ENTER TEXT CONTROL Z AT+CMSS = NN

4. HOW TO FORMAT AN SMSC AN SMSC IS A LOGICAL ME NUMBER e.g. 07976 123456 1) Always use International dialling code 44 7967 123456 2) Prefix by 19 to identify this as an international dialling code 19 44 7967 123456 3) Ensure there are always a pair of digits, if not back-fill with an F e.g. if we started with 07967 12345 we get 19 44 7967 12345F 4) Avoid national dialling codes as you never know where your code will be installed national dialling codes are prefixed by 18 5) Transmit as packed BCD, which requires the BCD nibbles to be swapped around to ensure the first digit sent is the first number in the string 91 44 97 76 21 43 65 6) Prefix this all with the byte count to tell the ME how long the SMSC number is FINAL STRING 07 91 44 97 76 21 43 65 OR JUST SEND 00 FOR THE LENGTH WHEN TRANSMITTING THE ME WILL USE THE DEEFAULT PRE-SET SMSC NUMBER

5. SMS SUBMIT SMSC 00

6. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics User Header If set it means that the User Data has a command header prefix which contains more instructions as to how to use the data field – e.g. Multi-part messaging

7. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Status Report Request that the SMSC advise the ME of the status of the SMS forwarding e.g. proof of delivery

8. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Validity Period How to intepret the VP field, relative, enhanced, absolute or not-used

9. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reject Duplicate SMS

10. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Message Type Indicator 01 = SMS Submit Reply path exists All commercial SMSC's ignore this

11. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reference Number 00 lets the ME decide

12. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reference Number 00 lets the ME decide Destination Address Length in digits excluding International dialling byte 0C International Dialling 19 Then the Number itself 44 7967 123456 0C 91 44 97 76 21 43 65

13. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reference Number 00 lets the ME decide Destination Address 0C 91 44 97 76 21 43 65

14. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reference Number 00 lets the ME decide Destination Address 0C 91 44 97 76 21 43 65 PID or Protocol Identifier e.g. SMS, Telefax, Telex, Voice, EMRES, Paging, Teletex, Universal Computer Interface, X400, email and a few more But we only use SMS which is 00

15. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reference Number 00 lets the ME decide Destination Address 0C 91 44 97 76 21 43 65 PID 00 DCS Data Coding Scheme

16. SMS SUBMIT SMSC 00 SUM_SUBMIT 11 Courtesy of Dream Fabrics Reference Number 00 lets the ME decide Destination Address 0C 91 44 97 76 21 43 65 PID 00 DCS 00 Validity Period AA = 4 days User data prefixed by a data length – NOTE 7-bit data is compressed into 8 byte memory

17. SMS DELIVER SMSC 0791449776214365 SMS_DELIVER 04 Courtesy of Dream Fabrics Sender Address 0C 91 44 97 76 21 43 65 PID 00 DCS 00 User data prefixed by a data length – NOTE 7-bit data is compressed into 8 byte memory Time Stamp – Year, Month, Day, Hours, Minutes, Seconds, Time Zone Reverse BCD