https://www.reddit.com/r/ATT/comments/1cu8352/unable_to_add_aarp_signature_program_discount_to/
Unable to add AARP Signature Program Discount to my cell phone ...
May 17, 2024 ... Comments Section ... I had this exact issue. The rep told me to wait, like, 10 days and try again. Went through the second time no problem.