Avaya SIP integration

Hi guys
I have a customer where I am just doing a check on their platform, they have a GVP and an Avaya, by some reason they didn’t integrate the Avaya to the Genesys platform…anyway…they use SIP integration with SIP Server.
Is there anyway I could pass KVPs from Genesys to Avaya and vice-versa using the SIP Link? Maybe the X-Genesys- mappings?
Any wild idea?

I remember working with a customer that had Avaya Session Manager some time ago and I think they used X-Genesys-UUI header for integration. I’ll try to reach them out to be sure.