Why do you need the AA at all? I would think that the inbound call route could just send the call to {li}. The digit map would strip whatever the source OBi sent, so you would get dial tone and could dial through the link. If, for some reason, the OBi doesn't work properly with an empty string as the destination, you could have the digit map output be a string that does essentially nothing on the PSTN line, e.g. turn off call waiting, enable outbound caller ID, etc. Then, after that was dialed out, you'd hear dialtone and could dial the actual number.
