Exiting in node.js after recursive function is done

I try to rewire my brain for async coding and I still I still seem to fail. Unfortunately I can't figure out how to do it properly in this case. Let me give an example:

var nconf = require('nconf');

 nconf.argv()
 .env();

 function runme(callback){
   var nummessages = nconf.get('SMS_MESSAGES');
   decodemessage(0, nummessages);
   callback();
 }

 function decodemessage(i, nummessages) {
  if( i < nummessages ) {
    var message = 'SMS_'+(i+1)+'_TEXT';
    var number = 'SMS_'+(i+1)+'_NUMBER';
    console.log('number: '+number);
    console.log('message: '+message);
    console.log('message text: '+ nconf.get(message));
    console.log('message number: '+ nconf.get(number));
    decodemessage(i+1);
  }
} 

runme(function(){
  process.exit(0);
});

This gets called by gammu-smsd which receives SMS messages and puts them into ENV vars and launches a script. This works fine as long as I run it on my own, return code seems to work as well. When I run it from gammu-smsd it fails and it looks like decodemessage is never executed. Some debug output shows that I do go into runme().

My guess is that the callback in runme() gets executed before the recursive decodemessage() call is done. Am I right and if so can someone explain how I can do that properly?

If you want to test run it like this:

node server.js --SMS_MESSAGES 2 --SMS_1_TEXT blabliblo --SMS_1_NUMBER=47796546546 --SMS_2_TEXT Iammessagetwo --SMS_2_NUMBER 12345678

Thanks