diff --git a/lib/utils/keyserver-call.js b/lib/utils/keyserver-call.js
--- a/lib/utils/keyserver-call.js
+++ b/lib/utils/keyserver-call.js
@@ -97,32 +97,39 @@
           args: Args,
           options?: ?CallServerEndpointOptions,
         ) => {
-          // TODO
+          const bindCallKeyserverEndpoint = (keyserverID: string) => {
+            const {
+              cookie,
+              urlPrefix,
+              sessionID,
+              connection,
+              lastCommunicatedPlatformDetails,
+            } = keyserverInfos[keyserverID];
+
+            const boundCallServerEndpoint = boundCallServerEndpointSelector({
+              dispatch,
+              currentUserInfo,
+              cookie,
+              urlPrefix,
+              sessionID,
+              connectionStatus: connection.status,
+              lastCommunicatedPlatformDetails,
+            });
+
+            return boundCallServerEndpoint(endpoint, data, options);
+          };
           if (keyserverCall.config.keyserverSelection === 'fanout') {
-            return Promise.resolve(undefined);
+            const promises = [];
+            for (const keyserverID in keyserverInfos) {
+              promises.push(bindCallKeyserverEndpoint(keyserverID));
+            }
+            return Promise.all(promises);
           }
+
           const keyserverID = keyserverCall.config.keyserverIDExtractor(
             ...args,
           );
-          const {
-            cookie,
-            urlPrefix,
-            sessionID,
-            connection,
-            lastCommunicatedPlatformDetails,
-          } = keyserverInfos[keyserverID];
-
-          const boundCallServerEndpoint = boundCallServerEndpointSelector({
-            dispatch,
-            currentUserInfo,
-            cookie,
-            urlPrefix,
-            sessionID,
-            connectionStatus: connection.status,
-            lastCommunicatedPlatformDetails,
-          });
-
-          return boundCallServerEndpoint(endpoint, data, options);
+          return bindCallKeyserverEndpoint(keyserverID);
         };
 
         return keyserverCall.actionFunc(callKeyserverEndpoint);