I use Vitelity for outgoing LD only. They allow you to set up sub-accounts, each with it's own name and password. You can go on their site and datafill what number you want sent out for each account. However, on occation a called party will get "Out of Area", it just depends on what gateway the call is passed to the POTS network. I know that in general PBX's that have a PRI link to a class 5 switch choose what number, extension or main, is sent out.