Cyber mega phone 2k only shows two videos

Why my cyber mega phone 2k only shows two videos? I try to dial with ‘echo’
and ‘video-conference’ but both of them show only two videos. I expected it can show 4 or more videos.

Please refer to the attached image of dialing the ‘echo’ extension.

Asterisk version: 15.4.1
Ubuntu version: 14.04

http.conf:

[general]
enabled=yes
bindaddr=0.0.0.0
bindport=8088
tlsenable=yes
tlsbindaddr=0.0.0.0:8089
tlscertfile=/etc/asterisk/keys/asterisk.pem

sip.conf:

[general]
udpbindaddr=0.0.0.0:5060
realm=freeswitch.ml
transport=udp,ws,wss
videosupport=yes

[199]
host=dynamic
secret=199
context=default
type=friend
encryption=yes
avpf=yes
force_avp=yes
icesupport=yes
directmedia=no
;disallow=all
;allow=opus
;allow=ulaw
;allow=vp8
allow=all
dtlsenable=yes
dtlsverify=fingerprint
dtlscertfile=/etc/asterisk/keys/asterisk.pem
dtlscafile=/etc/asterisk/keys/ca.crt
dtlssetup=actpass
rtcp_mux=yes

extensions.conf

[default]

exten => echo,1,Answer()
same => n,StreamEcho(3)
same => n,Hangup()

exten => video-conference,1,Answer()
same => n,ConfBridge(199)
same => n,Hangup()

exten => 200,1,Answer()
same => n,Playback(demo-congrats)
same => n,Hangup()

pjsip.conf:

[transport-wss]
type=transport
bind=0.0.0.0
protocol=wss

[199]
type=aor
max_contacts=5
;remove_existing=no

[199]
type=auth
auth_type=userpass
username=199
password=199 ; This is a completely insecure password. Do NOT expose this
; system to the Internet without utilizing a better password.

[199]
type=endpoint
context=default
direct_media=no
allow=all
aors=199
max_audio_streams=10
max_video_streams=10
webrtc=yes
dtls_ca_file=/etc/asterisk/keys/ca.crt
dtls_cert_file=/etc/asterisk/keys/asterisk.pem

You can’t use chan_sip. Ensure it is not loaded and that PJSIP is being used instead. You also need to ensure in the case of ConfBridge that the video_mode is set to sfu.