====== newsdp ======
**C → S → C {type:'newsdp', sdp:...}**

newsdp – modified SDP offer during a call.

Client wanting to change SDP during a call, eg to change media channels used, sends a newsdp message. Server forwards it to other end of call. That client should send an [[ixnx:wrtc:rtcgate:answer|answer]] message to accept the change.

arguments:
  * sdp - [[https://en.wikipedia.org/wiki/Session_Description_Protocol|SDP]] containing streaming media communications parameters
  * from - address of caller
  * to - address to call

optional argument:
  * from_dn - display name of caller

optional argument for group calls:
  * gid - group call ID