Move VoIP events to 22_voip_events

20_events is a huge as it is, this makes it easier to find what section
you actually want when editing.

specification/20_events.rst

@@ -88,69 +88,3 @@ users, they should include the displayname and avatar URL fields in these
 events so that clients already have these details to hand, and do not have to
 perform extra roundtrips to query it.
 
-Voice over IP
--------------
-Matrix can also be used to set up VoIP calls. This is part of the core
-specification, although is at a relatively early stage. Voice (and video) over
-Matrix is built on the WebRTC 1.0 standard. Call events are sent to a room, like
-any other event. This means that clients must only send call events to rooms
-with exactly two participants as currently the WebRTC standard is based around
-two-party communication.
-
-{{voip_events}}
-
-Message Exchange
-~~~~~~~~~~~~~~~~
-A call is set up with messages exchanged as follows:
-
-::
-
-   Caller                    Callee
- [Place Call]
- m.call.invite ----------->
- m.call.candidate -------->
- [..candidates..] -------->
-                           [Answers call]
-          <--------------- m.call.answer
-    [Call is active and ongoing]
-          <--------------- m.call.hangup
-
-Or a rejected call:
-
-::
-
-   Caller                      Callee
- m.call.invite ------------>
- m.call.candidate --------->
- [..candidates..] --------->
-                            [Rejects call]
-            <-------------- m.call.hangup
-
-Calls are negotiated according to the WebRTC specification.
-
-
-Glare
-~~~~~
-This specification aims to address the problem of two users calling each other
-at roughly the same time and their invites crossing on the wire. It is a far
-better experience for the users if their calls are connected if it is clear
-that their intention is to set up a call with one another.
-
-In Matrix, calls are to rooms rather than users (even if those rooms may only
-contain one other user) so we consider calls which are to the same room. The
-rules for dealing with such a situation are as follows:
-
- - If an invite to a room is received whilst the client is preparing to send an
-   invite to the same room, the client should cancel its outgoing call and
-   instead automatically accept the incoming call on behalf of the user.
- - If an invite to a room is received after the client has sent an invite to
-   the same room and is waiting for a response, the client should perform a
-   lexicographical comparison of the call IDs of the two calls and use the
-   lesser of the two calls, aborting the greater. If the incoming call is the
-   lesser, the client should accept this call on behalf of the user.
-
-The call setup should appear seamless to the user as if they had simply placed
-a call and the other party had accepted. Thusly, any media stream that had been
-setup for use on a call should be transferred and used for the call that
-replaces it.
-

specification/22_voip_events.rst

@@ -0,0 +1,65 @@
+Voice over IP
+-------------
+Matrix can also be used to set up VoIP calls. This is part of the core
+specification, although is at a relatively early stage. Voice (and video) over
+Matrix is built on the WebRTC 1.0 standard. Call events are sent to a room, like
+any other event. This means that clients must only send call events to rooms
+with exactly two participants as currently the WebRTC standard is based around
+two-party communication.
+
+{{voip_events}}
+
+Message Exchange
+~~~~~~~~~~~~~~~~
+A call is set up with messages exchanged as follows:
+
+::
+
+   Caller                    Callee
+ [Place Call]
+ m.call.invite ----------->
+ m.call.candidate -------->
+ [..candidates..] -------->
+                           [Answers call]
+          <--------------- m.call.answer
+    [Call is active and ongoing]
+          <--------------- m.call.hangup
+
+Or a rejected call:
+
+::
+
+   Caller                      Callee
+ m.call.invite ------------>
+ m.call.candidate --------->
+ [..candidates..] --------->
+                            [Rejects call]
+            <-------------- m.call.hangup
+
+Calls are negotiated according to the WebRTC specification.
+
+
+Glare
+~~~~~
+This specification aims to address the problem of two users calling each other
+at roughly the same time and their invites crossing on the wire. It is a far
+better experience for the users if their calls are connected if it is clear
+that their intention is to set up a call with one another.
+
+In Matrix, calls are to rooms rather than users (even if those rooms may only
+contain one other user) so we consider calls which are to the same room. The
+rules for dealing with such a situation are as follows:
+
+ - If an invite to a room is received whilst the client is preparing to send an
+   invite to the same room, the client should cancel its outgoing call and
+   instead automatically accept the incoming call on behalf of the user.
+ - If an invite to a room is received after the client has sent an invite to
+   the same room and is waiting for a response, the client should perform a
+   lexicographical comparison of the call IDs of the two calls and use the
+   lesser of the two calls, aborting the greater. If the incoming call is the
+   lesser, the client should accept this call on behalf of the user.
+
+The call setup should appear seamless to the user as if they had simply placed
+a call and the other party had accepted. Thusly, any media stream that had been
+setup for use on a call should be transferred and used for the call that
+replaces it.