diff --git a/README.md b/README.md
index 997af57..cd4b65d 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,12 @@ server {
 }
 ```
 
+By default, the app expects you to have a Matrix homeserver (such as [Synapse](https://matrix-org.github.io/synapse/latest/setup/installation.html)) installed locally and running on port 8008. If you wish to use a homeserver on a different URL or one that is hosted on a different server, you can add a config file as above, and include the homeserver URL that you'd like to use.
+
+Element Call requires a homeserver with registration enabled without any 3pid or token requirements, if you want it to be used by unregistered users. Furthermore, it is not recommended to use it with an existing homeserver where user accounts have joined normal rooms, as it may not be able to handle those yet and it may behave unreliably.
+
+Therefore, to use a self-hosted homeserver, this is recommended to be a new server where any user account created has not joined any normal rooms anywhere in the Matrix federated network. The homeserver used can be setup to disable federation, so as to prevent spam registrations (if you keep registrations open) and to ensure Element Call continues to work in case any user decides to log in to their Element Call account using the standard Element app and joins normal rooms that Element Call cannot handle.
+
 ## Development
 
 Element Call is built against [matrix-js-sdk](https://github.com/matrix-org/matrix-js-sdk/pull/2553). To get started, clone, install, and link the package:
@@ -62,8 +68,6 @@ yarn
 yarn link matrix-js-sdk
 ```
 
-By default, the app expects you to have [Synapse](https://matrix-org.github.io/synapse/latest/setup/installation.html) installed locally and running on port 8008. If you wish to use another homeserver, you can add a config file as above.
-
 You're now ready to launch the development server:
 
 ```
diff --git a/config/element_io_preview.json b/config/element_io_preview.json
index 3921304..39ed759 100644
--- a/config/element_io_preview.json
+++ b/config/element_io_preview.json
@@ -9,6 +9,10 @@
     "user_id": "@sfu:call.ems.host",
     "device_id": "YNZDLSEQMP"
   },
+  "posthog": {
+    "api_key": "phc_rXGHx9vDmyEvyRxPziYtdVIv0ahEv8A9uLWFcCi1WcU",
+    "api_host": "https://posthog-element-call.element.io"
+  },
   "rageshake": {
     "submit_url": "https://element.io/bugreports/submit"
   }