FWIW, if my information isn't outdated, FB requires users of the mobile partner portal to be actual mobile networks; airlines are not invited. I worked on this for WhatsApp before I left in 2019, and the airline text only free messaging did not fit with the WhatsApp special pricing/zero rating offering. Afaik, FB doesn't work with airlines on these offerings; the offerings started before I left and were a surprise to me when I was still informed about all the partners (because I had to add them to mailing lists and do other integration work)