prank phone call telemarketer

Is this a prank caller playing on my phone or a telemarketer?

for the past couple of months, I have been getting the strangest calls on my cell phone.I will get these random calls from different numbers most of the time, in my state, sometimes in my local area, and they will call and not say anything, or sometimes I ‘ll get a missed call, and it will be disconnected, or have a recording telling me that this person is unavailable, or cannot receive calls..so I couldnt figure out who it was, so I changed my cell number yesterday afternoon, I gave it to five people,which included my mom, my co worker, a romantic flame,(whom I dont really talk to ) and two of my close girlfriends..and today I get two of the same calls, call the number back its disconnected…I changed my number how could I still be getting these calls?Is this a telemarketer,or a prank caller?

Maybe A Spoof Card.They can hide the numbers and cant call them back

SpoofCard.com

Spoofing Resources
prank phone call telemarketer