Adam, I would love to, but it is not under our control. As a hotspot provider, that supplies tens of thousands of customers around the world, all using different IP addresses (that change), we simply cannot use the normal way of auth via the source IP. We do not own the customers (NAS) equipment, or have control over it, so we can't make them VPN all traffic to us or other way. This is why we're having to auth on Called-Station-Id instead of IP Address. If you can think of a better way, please advise. My original question remains, how can the module rewrite.called_station_id be used with a dynamic client setup? At the moment it does not work, so is that a bug, problem with my code, or something else? I appreciate your time and thank you for your advice. Thanks James