if REFER from FS has a hostname in the Refer-To preserve it on the outbound REFER

lib/call-session.js

@@ -774,10 +774,10 @@ Duration=${payload.duration} `
         const referredBy = req.getParsedHeader('Referred-By');
         if (!referredBy) return res.send(400);
         const u = parseUri(referredBy.uri);
-
+        const isDotDecimal = /^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$/.test(uri.host);
         let selectedGateway = false;
         let e164 = false;
-        if (gateway) {
+        if (gateway && isDotDecimal) {
           /* host of Refer-to to an outbound gateway */
           const gw = await this.srf.locals.getOutboundGatewayForRefer(gateway.voip_carrier_sid);
           if (gw) {
@@ -787,7 +787,7 @@ Duration=${payload.duration} `
             uri.port = gw.port;
           }
         }
-        if (!selectedGateway) {
+        if (!selectedGateway && isDotDecimal) {
           uri.host = this.req.source_address;
           uri.port = this.req.source_port;
         }

test/sip-tests.js

@@ -60,6 +60,7 @@ test('incoming call tests', async(t) => {
     await sippUac('uac-pcap-carrier-max-call-limit.xml', '172.38.0.20');
     t.pass('rejects incoming call with 503 when max calls per account reached');
 
+    /* switch off this env for remaining tests (JAMBONES_HOSTING is for Saas sts) */
     delete process.env.JAMBONES_HOSTING;
     await sippUac('uac-pcap-carrier-fail-ambiguous.xml', '172.38.0.40');
     t.pass('rejects incoming call with 503 when multiple accounts have same carrier witrh default routing')