Adds a retry logic when fetching conference numbers and pin.

react/features/base/util/httpUtils.js

+import { timeoutPromise } from './timeoutPromise';
+
 const logger = require('jitsi-meet-logger').getLogger(__filename);
 
+/**
+ * The number of milliseconds before deciding that we need retry a fetch request.
+ *
+ * @type {number}
+ */
+const RETRY_TIMEOUT = 3000;
+
 /**
  * Wrapper around fetch GET requests to handle json-ifying the response
  * and logging errors.
  *
  * @param {string} url - The URL to perform a GET against.
+ * @param {?boolean} retry - Whether the request will be retried after short timeout.
  * @returns {Promise<Object>} The response body, in JSON format, will be
  * through the Promise.
  */
-export function doGetJSON(url) {
-    return fetch(url)
+export function doGetJSON(url, retry) {
+    const fetchPromise = fetch(url)
         .then(response => {
             const jsonify = response.json();
 
 
             return Promise.reject(error);
         });
+
+    if (retry) {
+        return timeoutPromise(fetchPromise, RETRY_TIMEOUT)
+            .catch(response => {
+                if (response.status >= 400 && response.status < 500) {
+                    return Promise.reject(response);
+                }
+
+                return timeoutPromise(fetchPromise, RETRY_TIMEOUT);
+            });
+    }
+
+    return fetchPromise;
 }

react/features/invite/components/dial-in-summary/web/DialInSummary.js

             return Promise.resolve();
         }
 
-        return doGetJSON(`${dialInConfCodeUrl}?conference=${room}@${mucURL}`)
+        return doGetJSON(`${dialInConfCodeUrl}?conference=${room}@${mucURL}`, true)
             .catch(() => Promise.reject(this.props.t('info.genericError')));
     }
 
             URLSuffix = `?conference=${room}@${mucURL}`;
         }
 
-        return doGetJSON(`${dialInNumbersUrl}${URLSuffix}`)
+        return doGetJSON(`${dialInNumbersUrl}${URLSuffix}`, true)
             .catch(() => Promise.reject(this.props.t('info.genericError')));
     }
 

react/features/invite/functions.js

 
     const conferenceIDURL = `${baseUrl}?conference=${roomName}@${mucURL}`;
 
-    return doGetJSON(conferenceIDURL);
+    return doGetJSON(conferenceIDURL, true);
 }
 
 /**
 
     const fullUrl = `${url}?conference=${roomName}@${mucURL}`;
 
-    return doGetJSON(fullUrl);
+    return doGetJSON(fullUrl, true);
 }
 
 /**