They take incoming calls and make outgoing calls, they also can send and receive text messages. You can get the number by calling yourself or someone else with calller ID. The best way to get someone to answer them is to go into the settings, turn the volume up as loud as it can go and choose the most annoying ringtone you can find (Alarm is a good choice) and delete the call history. They might only ring about three times before going to some message about voicemail not being set up. I think they're only on during store hours though. If you find any other Demo IPhone numbers post them here. These are some I found
(408)550-4292
(408)839-2825
(408)839-3029
(408)839-5711
(408)839-3070
(408)839-2849
(408)839-3895
(408)839-3066
(408)307-8356
(408)839-1935