diff --git a/lib/call-session.js b/lib/call-session.js
index 737e713..e930ad0 100644
--- a/lib/call-session.js
+++ b/lib/call-session.js
@@ -31,7 +31,7 @@ const createBLegFromHeader = ({
     if (teams) {
       host = req.get('X-MS-Teams-Tenant-FQDN');
     }
-    else if (req.has('X-Preferred-From-User')) {
+    else if (req.has('X-Preferred-From-Host')) {
       host = req.get('X-Preferred-From-Host');
     } else if (register_from_domain) {
       host = register_from_domain;
@@ -312,7 +312,7 @@ class CallSession extends Emitter {
               const prependPlus = vc.e164_leading_plus && !this.req.calledNumber.startsWith('0') ? '+' : '';
               const scheme = transport === 'tls' && !process.env.JAMBONES_USE_BEST_EFFORT_TLS && o.use_sips_scheme ?
                 'sips' : 'sip';
-              const u = `${scheme}:${prefix}${prependPlus}${calledNumber}@${hostport};transport=${transport}`;
+              let u = `${scheme}:${prefix}${prependPlus}${calledNumber}@${hostport};transport=${transport}`;
               const obj = {
                 name: vc.name,
                 diversion: vc.diversion,
@@ -327,6 +327,11 @@ class CallSession extends Emitter {
                   password: vc.register_password
                 };
               }
+              if (vc.requires_register && vc.register_sip_realm?.length > 0) {
+                proxy = u;
+                u = `${scheme}:${prefix}${prependPlus}${calledNumber}@${vc.register_sip_realm};transport=${transport}`;
+                this.logger.debug({uri: u}, `using outbound proxy for this registered trunk: ${proxy}`);
+              }
               mapGateways.set(u, obj);
               uris.push(u);
               this.logger.debug({gateway: o}, `pushed uri ${u}`);