I believe you also need to register for their frequent flyer program (free?), though I'm not sure if you can just do that when you call.

About membership: https://www.jetblue.com/trueblue/FF_About.aspx

Register page: https://www.jetblueairways.com/cgi-bin/skylights.cgi?module=...

NOTE: they are changing the way their frequent-flyer program works this fall so you may want to read this as well to see what membership looks like in the long-term: https://www.jetblue.com/trueblue/newprogram/