diff --git a/changelog.d/5328.misc b/changelog.d/5328.misc
new file mode 100644
index 0000000000..e1b9dc58a3
--- /dev/null
+++ b/changelog.d/5328.misc
@@ -0,0 +1 @@
+The base classes for the v1 and v2_alpha REST APIs have been unified.
diff --git a/synapse/rest/client/v1/voip.py b/synapse/rest/client/v1/voip.py
index 0975df84cf..6381049210 100644
--- a/synapse/rest/client/v1/voip.py
+++ b/synapse/rest/client/v1/voip.py
@@ -29,6 +29,7 @@ class VoipRestServlet(RestServlet):
     def __init__(self, hs):
         super(VoipRestServlet, self).__init__()
         self.hs = hs
+        self.auth = hs.get_auth()
 
     @defer.inlineCallbacks
     def on_GET(self, request):