diff --git a/lib/middleware.js b/lib/middleware.js
index c82967f..f4b7642 100644
--- a/lib/middleware.js
+++ b/lib/middleware.js
@@ -1,6 +1,5 @@
 const debug = require('debug')('jambonz:sbc-outbound');
 const parseUri = require('drachtio-srf').parseUri;
-const srf = require('drachtio-srf');
 const Registrar = require('jambonz-mw-registrar');
 const {selectHostPort} = require('./utils');
 
@@ -61,10 +60,9 @@ function route(opts) {
         logger.info({details: reg}, `sending call to registered user ${aor}`);
         if (req.server.hostport !== reg.sbcAddress) {
           //proxy
-          const proxyAddress = selectHostPort(reg.sbcAddress, 'udp');
+          const proxyAddress = selectHostPort(reg.sbcAddress, 'tcp');
           logger.info(`proxying call to SBC at ${proxyAddress}`);
-          //req.proxy(`sip:${proxyAddress[1]}`);
-          req.srf.proxyRequest(req, `sip:${proxyAddress[1]}`);
+          req.srf.proxyRequest(req, `sip:${proxyAddress[1]};transport=tcp`);
           return;
         }
         req.locals.registration = reg;