PBX – James Batchelor

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…

Testing a New PBX

Recently I’ve had the opportunity to deploy and test a call centre PBX product to gauge if its viable to offer as a product and how it will sit within our infrastructure.

Installing and poking around the GUI is all well and good but to really find out how a PBX behaves it needs some traffic, to find outs its performance in regards to resources but also to find out what a vendor’s interpretation of an advertised feature actually is.

To generate sample calls, instead of registering handsets/softphones and dialling manually it would be better to automate this, and SIPp is the perfect tool for this.