William is correct in that its my provider's application's programming problem to determine which identifier is used on the claim or eligibility or cert request. For all of them (many numbers for a single provider), and in my case, many providers, I'll still have a single EDI address (well, actually 4 - 2 for batch and 2 for near-real-time).
I guess the real question is how the endpoint responder gets my EDI address. What they get in the transaction will be the unique provider identifier they have told me to use. If my common EDI address is not in the message for them to generate a response to me, then they would have to discover it which means I'd have to register all provider identifiers pointing to one of the 4 EDI addresses (now there's a really ugly thought...). I guess that's why I thought the ISA address would be my ultimate response address, but if that's not the case....... Dave Minch T&CS Project Manager John Muir / Mt. Diablo Health System Walnut Creek, CA (925) 941-2240
