gsmcodecs

Python codecs for 3GPP TS 23.038, as used in SMS PDU.

This module provides the GSM default 7-bit alphabet and language-specific shift tables as python codecs. A particular pairing of locking shift and single shift table is chosen by appending the relevant national language IDs to a base codec 'gsm23.038', separated by dashes (-). Eg:

• gsm23.038-0-2: GSM default alphabet with Spanish single shift table

Note: These codecs encode and decode one septet per encoded octet. For GSM style septet packing, refer to related PDU utilities.

Usage

>>> import gsmcodecs
>>> 'Buenos días'.encode('gsm23.038-0-2')
b'Buenos d\x1bias'
>>> b'Buenos d\x1bias'.decode('gsm23.038-0-2')
'Buenos días'

Exported Codecs

• gsm23.038-0-0: GSM 7 bit default alphabet w/ GSM 7 bit default alphabet extension table
• gsm23.038-X-Y: National language ID X locking shift table w/ National language ID Y single shift table
• gsm23.038: Alias of gsm23.038-0-0

Note: All possible pairings of locking and single shift tables will return a codec. In the case that a chosen language ID/table is not defined, a GSM default table will be substituted. For example, gsm23.038-2-2 is technically invalid since there is no locking shift table defined for the Spanish language, the returned codec would be equivalent to gsm23.038-0-2.

National Language IDs

The following national language IDs and character mappings are recognised. Refer to 3GPP TS 23.038, section 6.2 and Annex A:

CSV source files for each table are located under the 'lut/' directory.

Re-building Character Maps

Character maps for each of the default and national language tables can be re-computed from the source CSV files in the lut directory:

$ cd lut
$ make clean && make

Installation

$ pip install gsmcodecs