from node.js sip.js module

rport.js

var sip = require('sip');
var udp = require('dgram');
var assert = require('assert');
var util = require('util');

sip.start({}, function(rq) { sip.send(sip.makeResponse(rq, 500)); });

var socket = udp.createSocket('udp4');

socket.bind(6060);

function test1(success) {
  socket.on('message',function(msg, rinfo) {
    var rs = sip.stringify(sip.makeResponse(sip.parse(msg), 200));
    socket.send(new Buffer(rs), 0, rs.length, rinfo.port, rinfo.address);
  });

  sip.send(
    {
      method: 'OPTIONS',
      uri: 'sip:127.0.0.1:6060;transport=udp',
      headers: {
        cseq: {method: 'OPTIONS', seq:1},
        'call-id': 'hrbtch',
        to: {uri: 'sip:test@127.0.0.1'},
        from: {uri: 'sip:test@127.0.0.1'}
      }
    },
    function(rs) {
      assert.equal(rs.status, 200);
      success();
    }
  );
}

test1(function() { util.log("SUCCESS"); process.exit(0); })