chatty adds international prefix in some cases to the sender’s phonenumber (or text).
in my case, “15400” will turn into “+35815400”. this won’t happen in all numbers.
it should not add anything to the phonenumber what it gets from operator. it’s operator’s responsibility to add or change prefix if they do that.
as a hint, take a look at chatty-utils.c, function chatty_utils_check_phonenumber(++).
(link not added by me, link for “chatty” source code)
as a hint, i looked into source code and manage to trace the issue to the package “libphonenumber”. it has xml file containing rules for changes and most likely is compiled inside to the lib binary. however, chatty does not need to use that conversion.
(link not added by me, link for “libphonenumber” source code)