With over 300 million people, it's not surprising that pre-paid mobile numbers get re-used by the USA telecommunications companies.  Expired numbers enter a quarantine period and are then released into the pool of available numbers ready to be allocated to new pre-paid phone activations.




At usaprepaidsimcard.com.au we always provision a new mobile number for all of our USA phone sim cards - we never re-use our own sim cards.  However, occasionally a newly provisioned mobile number experiences calls to the previous owner of that number or it receives telemarketing calls.  




Why does this happen?




Perhaps the previous owner hasn't updated businesses and friends with their new mobile number. 




More likely, the previous owner's mobile number was on a telemarketing phone list.  Telemarketers in the USA can be quite brutal.  They use what are called "automatic diallers" which acts like a robot and dials literally thousands and thousands of different mobile number combinations, knowing that some will be successfully answered which are then connected to waiting operators ready to sell them something.  Have you been receiving calls but there's no one there?  These aren't people making prank calls - these are actually calls generated by the automatic dialler robot, but because there's no operator available to speak to you, you just hear silence.




On most mobile phones you can BLOCK incoming calls from particular numbers.  So if you've been receiving wrong number calls and the caller ID of that caller is displaying, it's easy to block them from calling again.




How to block incoming calls




On an iPhone, launch the Phone app, tap Recents along the bottom, find the number you want to block then tap the little "i" to the right of the number, then scroll down and tap "Block this Caller".  




On an Android, please consult the following helpful articles:




http://www.wikihow.com/Block-a-Number-on-Android




and




http://www.digitaltrends.com/mobile/how-to-block-phone-calls-on-your-android-smartphone/#!6Qoha




On other phones




Perform a Google search for your specific phone, such as "block incoming calls on Nokia C100".