VOIP calls, poor quality

vinylmusic

I placed a similar post on a different forum but I'm putting a cut down version of my post here hoping someone can help with the technical aspect of my problem

I have both Vonage and VoIPtalk and in both cases I find call quality very poor.
Firstly I subscribed to Vonage and got on their unlimited UK calls package.
I am using their wifi handset
This may sound a little complicated but I'm on a shared connection in a separate house. In the main house theres the phoneline then a Netgear 4port + wireless modem/router.
I dont have a phone in my house so I ran an ethernet cable directly from the router to my computer.
In order to use the Vonage wifi handset I connected a Fon router to the end of the cable and a belkin wireless adapter on my computer
The internet works fine withth an excellent 54.0Mbps signal but my vonage wifi leaves a lot to be desired. I set my vonage rate to maximum bandwidth gaining little improvement.
Sometimes its ok but a little quiet and other times its impossible to hold a conversation.
I just signed up to voiptalk and tried making calls through them using a USB VOIP phone which I bought from Maplins. I tried making a call to a landline but dont think much of the call quality there either.
I looked on voiptalk's help pages about call quality and they suggest both ends use a usb headset which doesnt help when calling landlines and theres no mention rhere about calling landlines

With both Vonage and Voiptalk I have a UK landline number with the area code of my choosing
I thought about going with Skype but their choice of area codes are very limited and I cant get one anywhere near the area I want which I find very surprising.

I have paid around £70 to Vonage who offer a 30 day no quibble money back guarantee
I've just got a few days left so I'm becoming desperate to find a solution.

If anyone can offer useful advice or an alternative provider I'd be very grateful. Please bear in mind I dont want to pay BT to install another phone line