Something

macro std-exten-ael( ext, dev ) {
    dia=Local/${ext}@outgoing_trusted/n;
    temp=${DB(CFW/${ext})};
    if ( ${temp} != 0 ) {
        dia=Local/${temp}@outgoing_trusted;
    };
    Dial(${dia},20,t);
    switch(${DIALSTATUS}) {
        case BUSY:
            Voicemail(b${ext});
            break;
        default:
            Voicemail(u${ext});
    };
};