Yealink OpenVPN to Draytek Router

The firewalls in front of our PBX’s are configured to only allow SIP traffic from UK IP addresses, this reduces the attack surface and is usually not an issue as almost all legitimate traffic is from the UK.

As we expand there is greater need for international connections, this is fine if they have a static WAN IP or FQDN, but the more recent requirements are for “home” users with phones on their residential connections where dynamic IPs are the standard.

Changing the whitelisted IP every time their IP changes is not only tedious, but gives poor service, plus due to recent events (here and here) I’m not prepared to open access to another country for a single extension.

In my case, these internationals are satellites of a UK based office, so the idea is having the overseas phone route all voice traffic through the UK office where its free to connect to the PBX…

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