I will receive 850 purchase order. In return, I need to generate and send 997 response, which include ISA/GS number. Where and who do I register with for this ISA id?
Thanks in advance
EDI systems are typically limited in scope to be between a few or even just 2 different organizations. These organizations need to decide beforehand on how much of the full EDI specification they're going to use, and how they're going to specify IDs. See here.
Also, see here. From this it looks like DUNS numbers or variants on them are common choices for IDs.
So your organization and the others need to just figure out if you're going to use DUNS number or ad-hoc made up numbers or what.