Caller ID said 'NOT IN USE'. I almost laughed. Someone chose that one. So, since it is not in use, I picked up, but said nothing, and was responded to in the same way. After about 20 seconds I just hung up.
Got a call on 4/22, but did not answer since unknown caller. Recently switch from sprint to verizon but kept same number. Never got these calls under previous cell phone provider. Also getting calls from a few other unknown numbers lately since the switch.