IPv6 not working

hi,

we try to connect this siptapi driver to our IPv6 only asterisk instance and it looks like IPv6 support is missing. 
As far as I could see this software is based on eXosip2/eXosip. From the eXosip2 repo:

https://github.com/aurelihein/exosip/blob/master/include/eXosip2/eX_setup.h

I can see IPv6 support. 