Basic hello-world extension doesn't work

[vk496]

Hello!

Im trying to make a number 6000 to answer and play a hello world sound, but I can only hear the ringing, no audio.

I added extra config to extensions_local.conf:

[dp_lookup]
exten => 6000,1,Ringing()
        same => n,Wait(4)
        same => n,Answer()
        same => n,Playback(hello-world)
        same => n,Hangup()

Other contexts always throws 404. With this one I'm able to hear the ringing at least, but pretty sure is not the correct one.

Tested with docker demo, and Android BareSIP (REGISTER, codec ulaw).

What I'm doing wrong?