Well after posting in another thread about how to call us toll free numbers for free from the uk I sorted it by signing up for fwd account.

I then used one of my linksys spa942's with the fwd account on it's second line to call the toll free support number for airwave and had a great 15 minutes conversation that went perfectly to solve a problem.

The tech at the other end didn't even know it was a voip call from the UK until I told him.

Ben