HOW TO make use of Movistar / O2's VoIP service

Hi community, recently I've changed from MasMovil ISP to O2 ISP, and my new ISP offers its VoIP service using a dedicated VLAN for it, the configuration is very simple but if you don't know what you've to do, it can be a headache.

The most important thing that you have to know is that you need make use of bird1-ipv4 to obtain the routes trough DHCP, and because of this, you have to create a second VLAN in WAN port (a bridge WAN with 2 VLANs for DSA devices) with a firewall zone for each one. At same time, I recommend you that if you don't have it yet, make a local (LAN) VLAN - Subnet only for your VoIP phone, softphones..., at this way your telephony is isolated from the rest of your local hosts, and of course, you can make use of your VPN server to use your VoIP service from outside of home.

Once time you have created the DHCP wan VLAN - Subnet and a local VLAN - Subnet, each one of them with a firewall zone associated, the only thing that you have to do is configure the redirection from your local VLAN - Subnet to your DHCP WAN VLAN - Subnet, and in the bird1-ipv4 config file (/etc/bird4.conf), delete the content or create a new file with the same name and put the next:

log syslog all;
protocol kernel {
scan time 20;
import all;
export all;
protocol device {
scan time 10;
protocol static {
export none;
filter voip_filter {
if net ~ then accept;
else reject;
protocol rip voip {
import all;
export filter voip_filter;
interface "put here your WAN DHCP VLAN among the quotes";

That's it, now you can use your ISP's VoIP service without problems.