int_if="ral0"
ext_if="tun0"
sip_ip="192.168.0.5"

scrub in all

altq on $ext_if priq queue { std, voip }
queue std priority 0 priq(default red)
queue voip priority 1 priq(red)

nat on $ext_if from $int_if -> ($ext_if:0)

rdr on $ext_if proto { tcp, udp } to port 5060 -> $sip_ip

pass quick on lo0

block in on $ext_if
pass quick on $int_if
pass out on $ext_if keep state queue std

pass out on $ext_if proto { tcp, udp } from $sip_ip port 5060 \
keep state queue voip
pass in on $ext_if proto { tcp, udp } from $sip_ip port 5060 \
keep state queue voip