Add more answers

supporting-docs/guides/2015-08-19-faq.md

@@ -484,7 +484,11 @@ Since events are extensible it is possible for malicious users and/or servers to
 
 ##### How do you do VoIP calls on Matrix?
 
-Voice (and video) over Matrix uses the WebRTC 1.0 standard to transfer call media (i.e. the actual voice and video traffic).  Matrix is used to signal the establishment and termination of the call by sending call events, like any other event.  Currently calls are only supported in rooms with exactly two participants - however, one of those participants may be a conferencing bridge.  We're looking at better ways to do group calling.
+Voice (and video) over Matrix uses the WebRTC 1.0 standard to transfer call media (i.e. the actual voice and video traffic).  Matrix is used to signal the establishment and termination of the call by sending call events, like any other event.  
+
+##### Are VoIP calls encrypted?
+
+WebRTC encrypts the media that's being sent. The signalling events that set up (and end) the call are encrypted if the room they were sent in has enabled encryption.
 
 ##### Do I need a TURN server?
 
@@ -638,13 +642,16 @@ disable encryption. We might experiment with ways to improve this in the future
 - for instance, by alerting the user next time they try to send a message in
 the room if encryption has been disabled.
 
+##### Why isn't end-to-end encryption enabled by default?
+
+We are deliberately keeping E2E opt-in during the beta as there is a small risk of undecryptable messages, and we don’t want to lull folks into a false sense of security.  As soon as we are out of beta, we will turn E2E on for any room with private history by default.  Another consideration is to give other clients a chance to catch up with E2E support before it's used by default.
+
 |
 
 ### QUESTIONS TO BE ANSWERED!
 
 This FAQ is a constant work in progress - patches and pull requests are *very* welcome to help us improve it.  Some of the frequent questions where we need to write an answer include:
 
- * How do I rename servers?
  * How do I change the TLS key of my server?
  * How do I maintain my synapse's DB (e.g. prune old conversations)?
  * How do I maintain my synapse's content repository (e.g. prune old content)?