See the settings sip.conf below

For Bria 3.5
We use h.264 codec:

[user1]
type=friend
host=dynamic
nat=no
qualify=no
dtmf=rfc2833
secret=1234
callerid=user1
canreinvite=no
context=internal
disallow=all
allow=alaw
allow=ulaw
allow=speex
allow=g729
allow=h264
videosupport=yes

[user2]
type=friend
host=dynamic
nat=yes
qualify=no
dtmf=rfc2833
secret=1234
callerid=user2
canreinvite=no
context=internal
disallow=all
allow=alaw
allow=ulaw
allow=speex
allow=g729
allow=h264
videosupport=yes

For Xlite
Just change h264 to h263 because Xlite does not support H.264 codec.

Sure, you will need to do
“sip reload” in the Asterisk CLI.