stun peer-name 172.16.31.2
stun protocol-group 1 basic
interface Loopback1
 ip address 172.16.31.1 255.255.255.255
interface Loopback2
 ip address 172.16.31.2 255.255.255.255
interface Serial0
 encapsulation stun
 stun group 1
 stun route all tcp 172.16.31.1
interface Serial1
 encapsulation stun
 stun group 1
 stun route all tcp 172.16.31.2