Updated to latest Vivox, made sure to reference UnityVivox.dll

Assets/Scripts/LobbyRelaySample.asmdef

         "GUID:fe25561d224ed4743af4c60938a59d0b",
         "GUID:4c3f49d89436d478ea78315c03159dcc",
         "GUID:f2d49d9fa7e7eb3418e39723a7d3b92f",
-        "GUID:060a730ab4d4804498f4a3146ed6f776",
-        "GUID:6087a74f6015aae4daed9a2577a7596c"
+        "GUID:6087a74f6015aae4daed9a2577a7596c",
+        "GUID:4ebbcb26024b547159a86c39de1a8fa5"
     ],
     "includePlatforms": [],
     "excludePlatforms": [],

Packages/manifest.json

   "dependencies": {
     "com.unity.2d.sprite": "1.0.0",
     "com.unity.collab-proxy": "1.9.0",
+    "com.unity.collections": "1.0.0-pre.6",
-    "com.unity.services.core": "1.1.0-pre.9",
+    "com.unity.services.core": "1.1.0-pre.10",
-    "com.unity.services.vivox": "15.1.150000-pre.6",
+    "com.unity.services.vivox": "15.1.150002-pre.1",
     "com.unity.sysroot.linux-x86_64": "0.1.15-preview",
     "com.unity.test-framework": "1.1.29",
     "com.unity.textmeshpro": "3.0.6",

Packages/packages-lock.json

       "url": "https://packages.unity.com"
     },
     "com.unity.collections": {
-      "version": "1.0.0-pre.5",
-      "depth": 1,
+      "version": "1.0.0-pre.6",
+      "depth": 0,
       "source": "registry",
       "dependencies": {
         "com.unity.burst": "1.5.4",
       "url": "https://packages.unity.com"
     },
     "com.unity.services.core": {
-      "version": "1.1.0-pre.9",
+      "version": "1.1.0-pre.10",
-        "com.unity.modules.unitywebrequest": "1.0.0"
+        "com.unity.modules.unitywebrequest": "1.0.0",
+        "com.unity.nuget.newtonsoft-json": "2.0.0"
       },
       "url": "https://packages.unity.com"
     },
       "url": "https://packages.unity.com"
     },
     "com.unity.services.vivox": {
-      "version": "15.1.150000-pre.6",
+      "version": "15.1.150002-pre.1",
       "depth": 0,
       "source": "registry",
       "dependencies": {