QBZappy,
Thanks for that site, I finally understand the idea.
I did some port forwarding to/from the Obi110, forwarded 5062-5063,53 & 69 to the PAP2
and lo and behold it is working perfectly now, Voice all round!
funnily enough it doesn't work unless I use an Outbound Proxy but it doesn't cut out after 10s and give me the Auth Error.
Thanks very much for the help.