diff --git a/bbb-lti/grails-app/services/org/bigbluebutton/BigbluebuttonService.groovy b/bbb-lti/grails-app/services/org/bigbluebutton/BigbluebuttonService.groovy
index 93ad700a6ba428949d56290a8ebf597c30df5fc1..1a9d90e29febb4a902ba56db71d97efb5e9cab98 100644
--- a/bbb-lti/grails-app/services/org/bigbluebutton/BigbluebuttonService.groovy
+++ b/bbb-lti/grails-app/services/org/bigbluebutton/BigbluebuttonService.groovy
@@ -198,7 +198,7 @@ class BigbluebuttonService {
     private String getCreateURL(String name, String meetingID, String attendeePW, String moderatorPW, String welcome, Integer voiceBridge, String logoutURL, String record, Integer duration, String meta ) {
         voiceBridge = ( voiceBridge == null || voiceBridge == 0 )? 70000 + new Random(System.currentTimeMillis()).nextInt(10000): voiceBridge;
 
-        String url = bbbProxy.getCreateURL(name, meetingID, attendeePW, moderatorPW, welcome, "", voiceBridge.toString(), "", logoutURL, "", record, duration.toString(), meta );
+        String url = bbbProxy.getCreateURL(name, meetingID, attendeePW, moderatorPW, welcome, null, voiceBridge.toString(), null, logoutURL, null, record, duration.toString(), meta );
         return url;
     }
 
diff --git a/bbb-lti/src/java/org/bigbluebutton/api/Proxy.java b/bbb-lti/src/java/org/bigbluebutton/api/Proxy.java
index 27d222af50d2679d439b8e757f98e471dd673e31..d6b0ca197e18a76954789681c7cda80cb27506f1 100644
--- a/bbb-lti/src/java/org/bigbluebutton/api/Proxy.java
+++ b/bbb-lti/src/java/org/bigbluebutton/api/Proxy.java
@@ -79,10 +79,16 @@ public class Proxy {
         url += "&attendeePW=" + attendeePW;
         url += "&welcome=" + getStringEncoded(welcome);
         url += "&logoutURL=" + getStringEncoded(logoutURL);
-        url += "&maxParticipants=" + maxParticipants;
         url += "&voiceBridge=" + voiceBridge;
-        url += "&dialNumber=" + dialNumber;
-        url += "&webVoice=" + webVoice;
+        if ( maxParticipants != null ) {
+            url += "&maxParticipants=" + maxParticipants;
+        }
+        if ( dialNumber != null ) {
+            url += "&dialNumber=" + dialNumber;
+        }
+        if ( webVoice != null ) {
+            url += "&webVoice=" + webVoice;
+        }
         url += "&record=" + record;
         url += "&duration=" + duration;
         url += "&" + meta;