After trial and error, I finally found how to set up World Exchange WXC VFX VOIP service on a softphone such as Counterpath's X-Lite or Eyebeam software. Unfortunately because I am using an OPEN SOURCE software instead of WXC supported devices, they are unable to provide support for my device/software.
I have included the setup configuration I used to successfully get it working, details below.

First step is to go to your softphone's settings.

1. Click on SIP account's (or add SIP account, your device will have a similar option)
2. Enter your display name (usually your phone number without leading 0 e.g. 79857XXX
3. Enter your username (usually same as display name)
4. Enter password
5. Enter Authorized username
6. Enter Domain

Domain Proxy Settings

1. Tick  Register with domain
2. Untick use as outbound proxy

than click ok.

Your softphone should now be setup to use VFX