It's all call routing, just make sure that on the inbound CSS from B you have access to the route patterns and that you're sending the digits to match them (or adjust them in either side to fit the route patterns).
It's no different than making sure you can reach a phone on the other end, CSS and what digits it has to play with determine where it will be routed.
HTH
java
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www.cisco.com/go/pdihelpdesk
HTH
java
if this helps, please rate
