First, you generally do not need any static routes for incoming calls. Mostly for outgoing only. So you should be able to safely remove any static route that is just for incoming (unless you are doing prefix or digit delete).
As for the busy signal, without looking at your config and watching a call, it would be difficult form to tell what is the problem. My guess, since you have one sroute for outgoing calls, there may be a conflict there and you need to make the sroutes specific to the calls. For example, the new sroute, instead of just *, you probably need to set the dn to = the forcediprouting did you set and set the priority to 25 and on the old sroute for outgoing set the priority to 20.
For any other assistance, you may email me directly.