The standard string codecs for converting from unicode to strs does not 
include the GSM 0.38 char mapping used by GSM services (like SMS).

I've written a codec for my use based on 'char_mapper' and the skeleton 
from gencodec.py, though it's a little complicated by the fact that the 
GSM encoding is semi-multibyte and not just a straight table look-up.

Gory details here in the comments:
http://www.unicode.org/Public/MAPPINGS/ETSI/GSM0338.TXT

The codec is available here:
http://github.com/jwishnie/pygsm/tree/f574f6db99c585f785f0c73a080814c043
2c6087/pygsm/gsmcodecs

Please consider it, or an optimized/improved version of it, for 
inclusion with the standard codecs distributed with python

You should provide your code as a patch against the Python trunk. Also,
unit tests should probably be part of Lib/test/test_codecs.py.

Are there many GSM libraries or applications out there? If not, maybe the codec is best left in your lib, since it wouldn’t be useful for a wide range of uses.

Note also that 2.7 is frozen, so substitute “py3k branch” for “trunk” in Antoine’s previous comment.

@jwishnie can you provide a patch for this, as without it the issue goes nowhere?

Since the codec has only been asked once, 5 years ago, I consider that there is not enough interested to put yet another encoding. Python already supports a lot of encodings.

It's easy to use your custom codec without having to modify Python, just register it:
https://docs.python.org/dev/library/codecs.html#codecs.register