FreePBX - Cisco SPA5xx Configuration

Hoping anyone can help me in regards to a problem I am having with FreePBX… I’m trying to setup a Shared Phone Book that can be accessed from all phones on my FreePBX Network. The CISCO SPA5xx have their own personal address books but I want to be able to replicate any changes.

I’ve been following the standard code as per below but it doesn’t work when I point to the xml file which I’ve stored online.

<Title>Name Of Directory</Title>
<Prompt>Prompt text.</Prompt>
<Name>Name of Person or Company</Name>

If anyone has any suggestions to this problem, that would be great. I’m not exactly technical in Linux so any basic instructions would be helpful.