diff --git a/app.js b/app.js
index 149f6ce..f9c2adf 100644
--- a/app.js
+++ b/app.js
@@ -5,8 +5,6 @@ assert.ok(process.env.JAMBONES_MYSQL_HOST &&
   process.env.JAMBONES_MYSQL_DATABASE, 'missing JAMBONES_MYSQL_XXX env vars');
 assert.ok(process.env.DRACHTIO_PORT || process.env.DRACHTIO_HOST, 'missing DRACHTIO_PORT env var');
 assert.ok(process.env.DRACHTIO_SECRET, 'missing DRACHTIO_SECRET env var');
-assert.ok(process.env.JAMBONES_RTPENGINES, 'missing JAMBONES_RTPENGINES env var');
-assert.ok(process.env.JAMBONES_FEATURE_SERVERS, 'missing JAMBONES_FEATURE_SERVERS env var');
 
 const Srf = require('drachtio-srf');
 const srf = new Srf();
@@ -25,20 +23,6 @@ const {
   connectionLimit: process.env.JAMBONES_MYSQL_CONNECTION_LIMIT || 10
 }, logger);
 
-// parse rtpengines
-srf.locals.rtpEngines = process.env.JAMBONES_RTPENGINES
-  .split(',')
-  .map((hp) => {
-    const arr = /^(.*):(.*)$/.exec(hp.trim());
-    if (arr) return {host: arr[1], port: parseInt(arr[2])};
-  });
-assert.ok(srf.locals.rtpEngines.length > 0, 'JAMBONES_RTPENGINES must be an array host:port addresses');
-
-// parse application servers
-srf.locals.featureServers = process.env.JAMBONES_FEATURE_SERVERS
-  .split(',')
-  .map((hp) => hp.trim());
-
 srf.locals.dbHelpers = {
   lookupAuthHook,
   lookupSipGatewayBySignalingAddress
diff --git a/lib/call-session.js b/lib/call-session.js
index 35d2a78..0201b04 100644
--- a/lib/call-session.js
+++ b/lib/call-session.js
@@ -12,10 +12,11 @@ class CallSession extends Emitter {
     this.res = res;
     this.srf = req.srf;
     this.logger = logger.child({callId: req.get('Call-ID')});
+
+    this.getFeatureServer = require('./fs-tracking')(this.srf, this.logger);
   }
 
   async connect() {
-    debug(`getRTPENGINE ${typeof getRtpEngine}`);
     const engine = getRtpEngine(this.logger);
     if (!engine) {
       this.logger.info('No available rtpengines, rejecting call!');
@@ -27,27 +28,31 @@ class CallSession extends Emitter {
     this.answer = answer;
     this.del = del;
 
+    const featureServer = this.getFeatureServer();
+    if (!featureServer) {
+      this.logger.info('No available feature servers, rejecting call!');
+      return this.res.send(480);
+    }
+    debug(`using feature server ${featureServer}`);
+
     this.rtpEngineOpts = makeRtpEngineOpts(this.req, isWSS(this.req), false);
     this.rtpEngineResource = {destroy: this.del.bind(null, this.rtpEngineOpts.common)};
     const obj = parseUri(this.req.uri);
-    const appServer = getAppserver(this.srf);
     let proxy, host, uri;
 
     // replace host part of uri if its an ipv4 address, leave it otherwise
     if (/\d{1-3}\.\d{1-3}\.\d{1-3}\.\d{1-3}/.test(obj.host)) {
       host = obj.host;
-      proxy = appServer;
+      proxy = featureServer;
     }
     else {
-      host = appServer;
+      host = featureServer;
     }
     if (obj.user) uri = `${obj.scheme}:${obj.user}@${host}`;
     else uri = `${obj.scheme}:${host}`;
     debug(`uri will be: ${uri}, proxy ${proxy}`);
 
     try {
-      // rtpengine 'offer'
-      debug('sending offer command to rtpengine');
       const response = await this.offer(this.rtpEngineOpts.offer);
       debug(`response from rtpengine to offer ${JSON.stringify(response)}`);
       if ('ok' !== response.result) {
diff --git a/lib/fs-tracking.js b/lib/fs-tracking.js
new file mode 100644
index 0000000..4cf74d5
--- /dev/null
+++ b/lib/fs-tracking.js
@@ -0,0 +1,80 @@
+const contacts = new Map();
+const noopLogger = {info: () => {}, error: () => {}};
+const debug = require('debug')('jambonz:sbc-inbound');
+
+module.exports = (srf, logger) => {
+  logger = logger || noopLogger;
+  let dynamic = true;
+  let idx = 0;
+
+  srf.options((req, res) => {
+    res.send(200);
+    if (req.has('X-FS-Status')) {
+      const uri = `sip:${req.source_address}:${req.source_address}`;
+      const status = req.get('X-FS-Status');
+      const calls = req.has('X-FS-Calls') ? parseInt(req.get('X-FS-Calls')) : 0;
+      if (status === 'open') {
+        if (!contacts) {
+          logger.info(`adding feature server at ${uri}`);
+          //stats.gauge('sbc.featureservers', contacts.size + 1);
+        }
+        logger.debug(`Feature server at ${uri} has ${calls} calls`);
+        contacts.set(uri, {pingTime: new Date(), calls: calls});
+      }
+      else {
+        if (contacts.includes(uri)) {
+          logger.info(`removing feature server at ${uri}`);
+          contacts.delete(uri);
+          //stats.gauge('sbc.featureservers', contacts.size + 1);
+        }
+      }
+    }
+  });
+
+  if (process.env.JAMBONES_FEATURE_SERVERS) {
+    dynamic = false;
+    process.env.JAMBONES_FEATURE_SERVERS
+      .split(',')
+      .map((hp) => hp.trim())
+      .forEach((uri) => contacts.set(uri, {active: 0, calls: 0}));
+    debug(`using static list of feature servers: ${[ ...contacts]}`);
+  }
+
+  if (dynamic) {
+    const CHECK_INTERVAL = 35;
+    setInterval(() => {
+      const dead = [];
+      const deadline = (new Date.now()).getTime() - 90000;
+      for (const obj of contacts) {
+        if (obj[1].pingTime.getTime() < deadline) dead.push(obj[0]);
+      }
+      dead.forEach((uri) => {
+        logger.info(`removing feature server at ${uri} due to lack of OPTIONS ping`);
+        contacts.delete(uri);
+      });
+
+      const keys = [ ...contacts.keys() ];
+      logger.debug({keys}, `there are ${keys.length} feature servers online`);
+      //stats.gauge('sbc.featureservers', contacts.size);
+    }, CHECK_INTERVAL * 1000);
+  }
+
+  return () => {
+    let selectedUri;
+
+    if (dynamic) {
+      const featureServers = [ ...contacts].map((o) => Object.assign({}, {uri: o[0]}, o[1]));
+      debug({featureServers}, 'selecting feature servers with least calls');
+      const fs = featureServers.sort((a, b) => (a.calls - b.calls)).shift();
+      if (!fs) logger.info('No available feature servers!');
+      else selectedUri = fs.uri;
+    }
+    else {
+      const featureServers = [ ...contacts].map((o) => o[0]);
+      debug({featureServers}, 'selecting feature servers from static list');
+      selectedUri = featureServers[idx++ % featureServers.length];
+      logger.debug(`selected ${selectedUri}`);
+    }
+    return selectedUri;
+  };
+};
diff --git a/package.json b/package.json
index b692424..962893e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sbc-inbound",
-  "version": "0.2.1",
+  "version": "0.3.0",
   "main": "app.js",
   "engines": {
     "node": ">= 10.16.0"