Setup Asterisk or FreePBX on VirtualBox and configure with Voipfone

We currently have a Cisco small business VOIP system (UC320) and are basically fed up with it. We are having intermittent issues with no audio on calls and we want to be able to have phones in other locations over our VPN.

We have been looking into alternatives and would prefer an in-house server-based option over a hosted service. We've given FreePBX a try and have managed to get it up and running on VirtualBox, but we have some wierd delay issues, it takes about 20 seconds to place a call to another extension or external number, and when you call in our SIP provider (Voipfone) sends the call to answerphone, but the FreePBX extension still rings about 20 seconds later, but of course the call is not there.

We'd like to get a quote for getting this setup properly. We have 9 different extensions and 3 call groups (with 3 corresponding inbound numbers). We plan on getting some new phone hardware (Ubiquiti VOIP phones), although if we can reuse some of our Cisco handsets that may be an option.

The deliverable would be a working VirtualBox virtual machine image with a working FreePBX config and documentation on how to backup the configuration files and make changes such as adding new extensions etc.