Someone

    $spliceext=array(
        'basetag'=>'n',
        'tag'=>'theend',
        'addpri'=>'',
        'cmd'=>new ext_macro('missedcallnotify')
      );
    foreach($ext->_exts['macro-hangupcall']['s'] as $_ext_k=>&$_ext_v){
      if($_ext_v['tag']!='theend'){continue;}
      $_ext_v['tag']='';
      array_splice($ext->_exts['macro-hangupcall']['s'],$_ext_k,0, array($spliceext) );
      break;
    }