Asterisk spandsp for fax,Chinese sent garbled

Hello, everyone
I set up the fax system with asterisk and spandsp, but the title (LOCALHEADERINFO) can not support the Chinese, the Chinese sent garbled.
Font encoding is not it?I use utf-8.

Thank you for your attention

Fax standards pre-date ISO10646, so it would not surprise me if Chinese fax machines do something like using gp2312 (or big5) but the actual fax standards specify a European oriented character set.

Unfortunately ITU-T charge reasonably heavily for standards, so I’m not going to check the source documents.

Is this a T.38 issue. If not, note that the actual fax encoding software for Asterisk is not part of Asterisk. There is a Digium commercial product, that has its own forum for the free taster, and Hylafax, which is supported elsewhere.

Even if the limitation is imposed by the open source Asterisk code, I think this would be treated as a feature request, wo you would have to submit code to get it on the issue tracker, and you would need to raise the issue on the developer mailing list, if you can’t provide code.