National Language Shift Table and GSM character set for SMPP

Introduction

Apart from standard features of SMPP 3.4, Power SMPP Software also supports National Language Single Shift and National Language Locking Shift functionality as per GSM 03.38 character set.

The national language tables are used for adding the special characters of certain languages that cannot be expressed using the GSM default 7 bit alphabet.

National Language Shift (Single/Locking) consists up to 26 different pages including most popular Turkish locking shift characters like ğ, Ğ, €, which can be sent at the cost of a single GSM-7 character, which is otherwise considered at unicode character and maximum of 70 characters can be sent in single SMS.

ESM class parameter must be defined to 64 which indicates that UDH is present in the message payload. Based on the Information Element identifier and language specific table, UDH is prepared and pre-pended in message payload.

 

03240101

03= UDHL, UDH Length

24= IEI, Information Element Identifier (National Language Identifier)

01= IEL, Information Element Length

01= IE, Information Element (Turkish National Language Single Shift indicator*)

 

 

00 Reserved
01 Turkish
02 Spanish (Single Shift not available, use default)

03 Portuguese
04 Bengali
05 Gujarati
06 Hindi
07 Kannada
08 Malayalam
09 Oriya
0A Punjabi
0B Tamil
0C Telugu
0D Urdu

Implementation

Each supported language has two sets of code pages and both can be used in isolation or combination. In general they are used in isolation and the single shift page mechanism is widely popular in the industry landscape.

The shift page is activated by using an ‘escape’ character. For GSM this is 0x1B (27). If no National Language Shift is indicated then default extended character set is assumed for encoding or decoding.

Based on UDH following logic should be implemented :

 

In case of mixed implementation, locking shift mechanism will follow till an escape character is encountered and resumed after the escape character. Single shift table should be followed for escape characters.