土耳其3GPP

TURKISH LANGUAGE CHARACTER PROBLEM IN MESSAGES In Turkey while writing messages, some Turkish Language characters (ç,ş,ı,ğ,ö,ü, Ç,Ş,İ,Ğ,Ö,Ü) allocate two characters. For that reason mobile phone subscribers in Turkey pay two message fee ,instead of one message fee .To avoid this situation Telecommunications Association take a decision. Short messages can be encoded using a variety of alphabets: the default GSM 7-bit alphabet and the 16-bit UTF-16/UCS-2 (Unicode Transformation Format) alphabet. Depending on which alphabet the subscriber has configured in the handset, this leads to the maximum individual Short Message sizes of 160 7-bit characters or 70 16-bit characters. Payload length is limited by the constraints of the signalling protocol to precisely 140 octets (140 octets = 140 * 8 bits = 1120 bits) which means Short Message sizes of for 7-bit is 160 (1120/7) characters or for 16-bit is 70 (1120/16) characters. Support of the GSM 7-bit alphabet is mandatory for GSM handsets and network elements, but some characters(12 character) like (ç,ş,ı,ğ,ö,ü, Ç,Ş,İ,Ğ,Ö,Ü) using in Turkish language must be encoded using the 16-bit Unicode character encoding. In Turkey if user wants to use the special Turkish character encoded using the 16-bit Unicode character encoding such as (ç,ş,I,ğ,ö,ü, Ç,Ş,İ,Ğ,Ö,Ü), the message length will automatically decrease from 160 characters to 70 characters. In this situation mobile phone subscribers in Turkey pay two message fee ,instead of one message fee . As a result of Turk Telekom and Vodafone actions, in 3GPP TS 23.040 and TS 23.038 standarts, some changes were done. As a result of that, made an addition for using the special character table in “user data header field” that was previously used for another aim. Two mechanism has been developed for backward compatability and maximum character usage. In order to use the 2 mechanism, “header definition” allocate 5 characters, thus both two mechanism’s maximum message size decreases to 155 characters. 1.) First mechanism (single shift) provide us to change the existing default GSM 7-bit alphabet table to expansion table that is specific to language. Characters using in the message, changes with the similar character in the existing default GSM 7-bit alphabet table. Such as ( ç->c, ş->s, ı->i, ğ->g, ö->o, ü->u, Ç->C, Ş->S, İ->I, Ğ->G, Ö->O, Ü->U ). Every character used from the National Language Single Shift Table will need an additional character to identify the escape to the National Language Single Shift Table. The available 155 character capacity of a single message will therefore be reduced accordingly. This reduction of overall message length also applies when using characters from the GSM 7 bit default alphabet extension table (see subclause 6.2.1.1) when the National Language Single Shift IE is not used. 2.) Second mechanism (locking shift) provide us to change the existing default GSM 7-bit alphabet table to main table that is specific to language.Thus characters that is not used in existing alphabet will change the character that is specific to language, and all characters allocate only 7 bits. Consequently mobile phone subscribers in Turkey won’t pay two message fee ,instead of one message fee . Every character in the National Language Locking Shift Table will use an additional character. The available 152 character single message length will therefore be reduced accordingly. This reduction of overall message length also applies when using characters from the GSM 7 bit default alphabet extension table (see subclause 6.2.1.1) when the National Language Single Shift IE is not used. As a conclusion, in accordance with the Telecommunications Association 's decision, all mobile phones sold in Turkey must have been satisfied these two mechanism described above by the manufacturers until 01.07.2008. For your kind attention.