sipRefer()
Transfer a sip dial-in call to another sip endpoint outside Daily. For moving the call within Daily, use sipCallTransfer().
Note that the participant who initiates this must be an owner or an admin.
Each call to `sipRefer()` API is billed separately. contact support to understand pricing
example scenarios
Call transfer using SIP REFER
- user dials in to 
room-a's SIP URI sipRefer()API is called with destinationsip_uri- sip device disconnects from 
room-aand the destinationsip_uristarts ringing. 
sipRefer(params)
Parameters
sessionIdthe participant of the sip/pstn participant we want to transfer.toEndPointdestination sip/pstn where call will be transferred.
Compatibility:
Prebuilt
Custom