diff --git a/src/api/index.js b/src/api/index.js
index 86f3a07..e1adce1 100644
--- a/src/api/index.js
+++ b/src/api/index.js
@@ -3,7 +3,7 @@ const cors = require('cors');
 const bodyParser = require('body-parser');
 const publicContent = require('../../app.json');
 
-module.exports = ({ config, realm, messageHandler }) => {
+module.exports = ({ config, realm, messageHandler, randomId }) => {
   const authMiddleware = require('./middleware/auth')({ config, realm });
 
   const app = express.Router();
@@ -16,7 +16,7 @@ module.exports = ({ config, realm, messageHandler }) => {
     res.send(publicContent);
   });
 
-  app.use('/:key', require('./v1/public')({ config, realm }));
+  app.use('/:key', require('./v1/public')({ config, realm, randomId }));
   app.use('/:key/:id/:token', authMiddleware, jsonParser, require('./v1/calls')({ realm, messageHandler }));
 
   return app;
diff --git a/src/api/v1/public/index.js b/src/api/v1/public/index.js
index a47a371..8a09752 100644
--- a/src/api/v1/public/index.js
+++ b/src/api/v1/public/index.js
@@ -1,12 +1,13 @@
 const express = require('express');
 
-module.exports = ({ config, realm }) => {
+module.exports = ({ config, realm, randomId }) => {
   const app = express.Router();
 
   // Retrieve guaranteed random ID.
   app.get('/id', (req, res) => {
     res.contentType = 'text/html';
-    res.send(realm.generateClientId());
+    console.error('src/api/v1/public/index.js', randomId);
+    res.send(realm.generateClientId(randomId));
   });
 
   // Get a list of all peers for a key, enabled by the `allowDiscovery` flag.
diff --git a/src/index.js b/src/index.js
index ea3d9e0..0ec5087 100644
--- a/src/index.js
+++ b/src/index.js
@@ -6,11 +6,11 @@ const defaultConfig = require('../config');
 const WebSocketServer = require('./services/webSocketServer');
 const Realm = require('./models/realm');
 
-const init = ({ app, server, options }) => {
+const init = ({ app, server, options, randomId }) => {
   const config = options;
   const realm = new Realm();
   const messageHandler = require('./messageHandler')({ realm });
-  const api = require('./api')({ config, realm, messageHandler });
+  const api = require('./api')({ config, realm, messageHandler, randomId });
 
   const { startMessagesExpiration } = require('./services/messagesExpire')({ realm, config, messageHandler });
   const checkBrokenConnections = require('./services/checkBrokenConnections')({
@@ -62,7 +62,7 @@ const init = ({ app, server, options }) => {
   checkBrokenConnections.start();
 };
 
-function ExpressPeerServer(server, options) {
+function ExpressPeerServer(server, options, randomId) {
   const app = express();
 
   options = {
@@ -80,13 +80,13 @@ function ExpressPeerServer(server, options) {
         'can\'t start PeerServer');
     }
 
-    init({ app, server, options });
+    init({ app, server, options, randomId });
   });
 
   return app;
 }
 
-function PeerServer(options = {}, callback) {
+function PeerServer(options = {}, callback, randomId) {
   const app = express();
 
   options = {
@@ -114,7 +114,7 @@ function PeerServer(options = {}, callback) {
     server = http.createServer(app);
   }
 
-  const peerjs = ExpressPeerServer(server, options);
+  const peerjs = ExpressPeerServer(server, options, randomId);
   app.use(peerjs);
 
   if (callback) {
diff --git a/src/models/realm.js b/src/models/realm.js
index fbc4e84..e0355fd 100644
--- a/src/models/realm.js
+++ b/src/models/realm.js
@@ -42,10 +42,12 @@ class Realm {
     this._messageQueues.delete(id);
   }
 
-  generateClientId () {
-    const randomId = () => (Math.random().toString(36) + '0000000000000000000').substr(2, 16);
+  generateClientId (_randomId) {
+    const randomId = typeof _randomId === 'function' ?
+      () => _randomId :
+      () => (Math.random().toString(36) + '0000000000000000000').substr(2, 16);
 
-    let clientId = randomId();
+    let clientId = randomId(randomId)();
 
     while (this.getClientById(clientId)) {
       clientId = randomId();