To begin you need to understand a couple things about avaya 96xx sip phones. They function in 2 ways. SIPPING-19 or Avaya SIP with advanced features including PPM . So when they boot up they one of the things it does is it needs to determine what Sip Features are going to be supported. This is done by sending out a SIP command and waiting for response. Since asterisk does not recognize this command it does not respond so the avaya phone determines it’s not connecting to an Avaya PBX so it defaults to just supporting the SIPPING-19 Features. So in order to enable Contact list, speed dial, history we need to get the phone to enable more than just SIPPING-19. A good place to understand the boot sequences of the phones Andrew Prokop has some really good blogs that go over this.
The Steps Involved in Booting an Avaya SIP Telephone https:// andrewjprokop.wordpress.com/2014/03/03/the-steps-involved-in-booting-an-avaya-sip-telephone/
it takes a bit of Work to get the soft buttons working on avaya phones with Freepbx. if your up to it see my post Avaya 96x1 extended Features