diff --git a/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java b/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java
index 54d48cf93..9e7d6501e 100644
--- a/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java
+++ b/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java
@@ -135,6 +135,10 @@ public class AccountController {
         throw new WebApplicationException(Response.status(403).build());
       }
 
+      if (accounts.isRelayListed(number)) {
+        throw new WebApplicationException(Response.status(417).build());
+      }
+
       Device device = new Device();
       device.setId(Device.MASTER_ID);
       device.setAuthenticationCredentials(new AuthenticationCredentials(password));
diff --git a/src/main/java/org/whispersystems/textsecuregcm/storage/AccountsManager.java b/src/main/java/org/whispersystems/textsecuregcm/storage/AccountsManager.java
index 345569f7f..fdfe7b13f 100644
--- a/src/main/java/org/whispersystems/textsecuregcm/storage/AccountsManager.java
+++ b/src/main/java/org/whispersystems/textsecuregcm/storage/AccountsManager.java
@@ -90,6 +90,13 @@ public class AccountsManager {
     else                 return Optional.absent();
   }
 
+  public boolean isRelayListed(String number) {
+    byte[]                  token   = Util.getContactToken(number);
+    Optional<ClientContact> contact = directory.get(token);
+
+    return contact.isPresent() && !Util.isEmpty(contact.get().getRelay());
+  }
+
   private void updateDirectory(Account account) {
     if (account.isActive()) {
       byte[]        token         = Util.getContactToken(account.getNumber());