[Asterisk-Dev] IAX spec: Text formats and character sets

[Olle E. Johansson]

Good morning, bonjour, god dag!

The IAX spec has to be more specific in regards to character sets
used in various messages.

The numbers and CID names are specified as "ASCII encoded text".
There's not spec of HTML text format. That assumes ISO-8859-1, 8 bit.

* ASCII is 7 bit only. A-Z
* As far as I know, Caller ID Name is also ISO 8859-1, 8 bit.
* SIP is UTF8, meaning I can include not only Swedish ÅÄÖ but almost
   any character set, except the secret magic runes...

We need to set an Asterisk /IAX2 standard for text frames, "numbers" and 
caller ID names. Asterisk is more and more becoming an international 
project and we need to work this out before we've come too far in the
"all text strings are US ASCII" soup and can't clear this up. I've been 
working quite a long time with network communication and have carried a 
large number of Swedish keyboards to US programmers that needed to learn 
that there where more characters in the world than A-Z and even stranger 
keyboards (as the participants on Astricon Training in Stockholm quickly 
had to learn :-) )

I would like to see that Asterisk internally uses two sets of names and 
phone numbers - one alphanumeric UTF 8 and one ASCII. That way we can 
handle both SIP and IAX2 and know what kind of object we're handling.
Right now, the SIP channel happily adds UTF8 caller ID names to the 
CID*name field, or UTF8 extensions/phone numers/user names to the called 
extension field.

Leif Madsen and I have written a proposal that we would like the 
community to review, called alphaextensions. In this, we try to define a 
way to add proper handling of international character sets in extensions 
(a la SIP) without breaking backwards compatibility with the current 
dialplans and applications within Asterisk.

This proposal is available at
http://edvina.net/asterisk/alphanumericextensions.pdf

...and we would very much like input on that. This became even more 
important after browsing through the IAX spec (IAX2 spec? :-) ).

Another quick comment: I think we should format the IAX spec not as an 
Internet Draft, but as an Informational RFC like the early NFS RFCs, 
since the wording of the first paragraphs tells us that it will never be 
published as an IETF draft any way...

/Olle