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

The Short Message Service Centre SMSC

ME ME

MASTMAST

SMSC

LOCAL MOBILE

NET

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.

INTRODUCTION TO DATA OVER GSM

ANALOGUE – e.g V22 etcSHORT MESSAGE SERVICE – SMSGPRS

BASIC SMS COMMANDSAT+CMGS=”+447967123456”>ENTER TEXTCONTROL Z

AT+CMGR=NN

AT+CMGD=NN

AT+CMGW=”+44796123456”>ENTER TEXTCONTROL Z

AT+CMSS = NN

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 TRANSMITTINGTHE ME WILL USE THE DEEFAULT PRE-SET SMSC NUMBER

SMS SUBMIT

SMSC 00

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11

Courtesy of Dream Fabrics

User HeaderIf 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

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11


Status ReportRequest that the SMSC advise the ME of the status of the SMS forwarding e.g. proof of delivery

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11


Validity Period

How to intepret the VP field, relative, enhanced, absolute or not-used

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11


Reject Duplicate SMS

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11


Message Type Indicator01 = SMS Submit

Reply path existsAll commercial SMSC's ignore this

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11


Reference Number 00 lets the ME decide

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11



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

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11



Destination Address 0C 91 44 97 76 21 43 65

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11




PID or Protocol Identifiere.g. SMS, Telefax, Telex, Voice, EMRES, Paging, Teletex, Universal Computer Interface,X400, email and a few moreBut we only use SMS which is 00

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11




PID 00

DCSDataCodingScheme

SMS SUBMIT

SMSC 00

SUM_SUBMIT 11




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

SMS DELIVER

SMSC 0791449776214365

SMS_DELIVER 04


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 ZoneReverse BCD

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

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