DO NOT CALL BACK! The minute you do even though you hit 2, you have just given them the okay to continue to harass you! They will know your number is a working number!
Got a call to my cell phone just now (10:30 PM Local Time). They hung up after one ring before I could even see who was calling. If this is a telemarketer, they aren't supposed to call here after 9:00 pm.