This is the entry in the pjsip.endpoint.conf file
[201]
type=endpoint
aors=201
auth=201-auth
allow=ulaw
context=from-internal
callerid=device <201>
dtmf_mode=info
use_avpf=no
ice_support=no
media_use_received_transport=no
trust_id_inbound=yes
media_encryption=no
rtp_symmetric=yes
rewrite_contact=yes
media_encryption=dtls
dtls_verify=fingerprint
dtls_cert_file=/etc/asterisk/keys/default.pem
dtls_ca_file=/etc/asterisk/keys/ca.crt
[202]
type=endpoint
aors=202
auth=202-auth
allow=ulaw
context=from-internal
callerid=device <202>
dtmf_mode=info
use_avpf=no
ice_support=no
media_use_received_transport=no
trust_id_inbound=yes
media_encryption=no
rtp_symmetric=yes
rewrite_contact=yes