At hand phone GSM there is facility to data access applies serial connection, for data access is required by instruction sequence at interface hand phone. ETSI (European Telecommunication Standard Institute) that is the instruction standard in technical specification GSM. instruction phone is started with character AT and terminated with enter or 0Dh. Command received will be response with receiving of data ‘OK’ or ‘ Errors’. Applying AT Command important for SMS is:
AT+CMGS : to send SMS
AT+CMGL : to verify SMS
AT+CMGD : to vanish SMS
AT COMMAND for SMS usually followed by I/O started by units PDU. Streaming data or from SMS-CENTER must be in the form of PDU (Protocol Data Unit). PDU contains hexadecimal number what express language I/O. PDU consisted of some Header. Header to send SMS to SMS-CENTER differs from SMS received from SMS-CENTER. PDU send SMS to SMS-CENTER. There is eight header to send SMS, that is:
1. Number SMS CENTER
This first header divided to become three sub header
a. Number of couples hexa decimal SMS-CENTER in number hexa.
b. International Code and national code, header for national it is 81 and international is 91.
c. Number SMS-CENTER itself in couple hexa is turned over repeatedly.
example:
if number SMS-CENTER 0875400000
hence, writing national.
for writing of Heksa from SMS-CENTER 0875400000 becoming –>
80-57-04-00-00
so that writing as complete this is:
06818057040000 ==> value 06 showing there is 6 value tide
that is Code National(1 tide) + number SMS-CENTER(5 tide).
writing international
for writing of Hexsa from SMS-CENTER 62875400000 becoming –>
26-78-45-00-00-F0
so that writing as complete his is:
07912678450000F0 ==> value 07 showing there is 7 tide value that is Code International(1 tide) + number SMS-CENTER(6 tide).
2. Type SMS
Type AS OF neodymium SMS : 1 thus its a hexsa number is 01.
3. Number Reference SMS
Reference number gives value 0, causing the heksa value 00. Because later automatically will be given value by SMS-GATEWAY
4. Number Phone Acceptor
Writing of PDU at writing of phone number as follows:
a. Number of number decimal phone numbers gone to in number hexsa.
b. National or international Code. For National with code: 81. And international with code: 91
c. Number phone gone to in couple heksa is turned over repeatedly.
Example:
If phone number gone to be 081227153432.
For National Code :
at number gone to National is 081227153432 ==> the numbers 12 numbers ==> value hexsa 0C, and couple heksa from phone number gone to 80-21-72-51-43-23, hence writing is : 0C81802172514323
For International Code:
at number gone to International is 6281227153432 ==> number of numbers there are 13 numbers ==> value heksa 0D, and couple hexsa from phone number gone to 26-18-22-17-35-34-F2, hence writing it is : 0D91261822173534F2
5. form of SMS
0 ==> 00 –> SMS is sent in the form of SMS.
1 ==> 01 –> SMS is sent in the form of telex.
2 ==> 02 –> SMS is sent in the form of fax.
6.Scheme Encoding Data I/o
This time there are many the SMS Gateway in marketing applies 7 bit so that we apply code : 00, if there are still SMS Gateway which applies code bigger than 0 changed to Hexsa.
7. Duration Before SMS EXPIRED
If part of this skip, meant we are to derestricted time implementation of SMS.
8. Contents Of SMS
at part contents of SMS there are two sub Header.
a. Bulk length or number of contents of SMS
for example: to say ” Hi..” ==> there is 5 letter –> 05
b. Contents of in the form of number pair heksa phone or SMS-GATEWAY is having scheme encoding 7 bit to mean if we are etic a letter from key pad we make 7 successive I/O number, applies convertion ASCII to Heksa can. Or applies convertion itself that is:
first step : changes it becomes code 7 bit.
second step : changes code 7 bit to become 8 bit, what represented by couple hexsa.
so conclusion from writing of this PDU by writing down all sequences as follows :
Number SMS-CENTER – Type SMS – Reference number SMS – Number phone acceptor – Form Of SMS – Scheme Encoding Data I/O – duration before SMS expired – Contents Of SMS
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