AT&T SYNJ HANDSET ONLY CORDLESSFOR SYNJ SB67118 HANDSET PAIRS TO SB671181 to 4 line capacity with lighted line indicators100 name/number phonebook directory with rapid scroll and 50 name/number caller ID history (activation required)Expandable up to 10 handsetsVolume control for handset, headset and ringerPage, intercom and call transfer between stations Push-to-talk intercom3-party conferencing (for multi-line systems)Low battery indicator10 speed dial and 10 intercom number locations English/Spanish setup menu 2.5mm headset compatible