Accented Letters | GSM 03.38 charset

Hello, would you help me please with a charset issue? I want to use accented characters when sending french message. Accented letters would be truncated, deleted or replaced upon receiving at destination numbers.

which gateway are you using?

I am using Gammu.
I tried without success to edit UTF-8 Characters to be encoded in “/var/www/html/playsms/lib/fn_core.php”.
I didn’t find any other char table than the one found at
Looks like I am not the only one facing this issue. Please have a look at