This is a sample configuration using chan_PJSIP running on one of our test FreePBXs.
General:
username = techprefix
password = password
auth is outbound
registration is send
sip server is your preferred flowroute registration domain from your account
port is 5060
context is from-pstn
transport is 0.0.0.0-udp
Advanced:
DTMF is RFC 4733
Match(permit) = 147.75.60.160/28, 34.210.91.112/28, 34.226.36.32/28, 147.75.65.192/28
Support path yes
rtp symmetric yes
Everything else should be a default.
