I got it working, seems I was trying to make it too complicated by altering a lot of settings local first. Reset everything using Obitalk, registered Sp1 and just added the one forward, now the redial works. Only two other issues:
Want to get intercom redirected, as in a local intercom signal is sent and that is rerouted as a call would be. And there is quite a bit of delay before the call is rerouted, I think I remember seeing some settings that control that as well.
EDIT:
All working great now. Set RingThreshold to lowest and have reduced RingDelay to 0 as callerid won't be necessary for this line. Thanks for the help.