Not showing spanish special characters in the callerid with asterisk

[arcanos]

Dear friends

I've been trying to fix this, but at the momento I've been uncapable. We are a spanish company that uses Yealink phones with asterisk. Our problem is that if the caller name has an special character (áéíóúñ...), when the call enters in the destination phone, the name doesn't show correctly.

One easy example...

exten => 150,1,Set(CALLERID(name)=María)
same => n,Dial(SIP/usernamefor150,45,two)
same => n,HangUp()

... when you dial 150, in the LCD appears...

Mar?

... instead of...

María

Also happens with realtime extensions or if you define it in sip.conf. Any ideas?

Thanks in advance

Alberto