Nick formulated the question :[color=blue]
> Yes I have being playing with gateways. I can get VoipCheap working as a
> gateway but can't get the Caller Id spoofing working when in this mode.[/color]

Courtesy of Mike Sun:

Instead of entering just e.g. sip.voipcheap.com enter
[phone-number]@sip.voipcheap.com where [phone-number] is one of your
registered numbers with the provider. Thus one is effectively entering
both "User ID" and "Auth ID" in the Gateway setup.

(presumably you leave the [] brackets off)

You may also have to play around with the number - try 01xxxxxxxxx
format and 00441xxxxxxxxx etc.