You can also register a trunk on the 8003, so you can have an incoming call without setting up sip on the 8003 device., But there is no audio...
I setup a trunk in asterisk to register as extension my first indoor panel, that works with audio...
Advantage, early video still works on indoor panels, and if asterisk goes down, then the system still works, so basically I'm using the private sip protocol , instead of configuring sip itself. Much stabler and also hikconnect cloud will still work