Add Rebtel-like/localphone-like "Local Access" Feature To A2Billing-based site

I need a very experienced professional on A2Billing & Asterisk that has proven work history on the above feature. The scenario: Customer chooses a local U.S number in customer portal and associates it with a call contact in an international location say India. The next time this customer calls his India buddy, he just dials the U.S number directly. No PIN needed, NO access number needed. In other words, a set of DIDs(say 5 or 10) are configured in A2Billing to be shared by all customers for this purpose. Routing rules to be developed in this project. Please include details of you planned approach on this as well as evidence of prior work. Thanks very much and welcome to BID!!