Does anyone here use Asterisk or Trixbox?

I'm having trouble understanding the the dial rules for outbound routes?

Does anyone know of any good tutorials with British dialing rule examples for the various trunks I've setup? (I'm begining to think I've looked at this so long now I can't see the wood for the trees. )

I have been using a sipura 3000 ata for a while and it's easy enough to setup dialplans on this. I have for example 080* numbers going through my pstn, 07* mobile numbers going through voipfone, 00* - international numbers going through voipcheap.com, uk numbers 01* going through voipcheap.com, premium rates numbers blocked, etc, but I haven't been able to find any examples how to do this in trixbox.