With over 300 million people, it's not surprising that pre-paid mobile numbers need to get re-used at some point by the USA telecommunications companies. There's a limit to how many mobile numbers there can be. 


Expired mobile numbers enter a quarantine period of several months 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 activate our SIM Cards with a new mobile number - we never re-use our own SIM cards.  However, occasionally a newly provisioned mobile number experiences wrong number calls.  


Why does this happen?


Sometimes you might receive phone calls from telemarketers. They use what are called "auto-diallers" that generate random telephone numbers. Basically this is a computer program that 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. Because mobile numbers are of a particular format it's very easy to randomly generate thousands of phone numbers and call them all. Some will be valid (and will be answered), and some will be invalid and won't work. But the telmarketers don't care. 


It's a bit like spam emails -- the spammer hasn't hacked your email address or found it on a list -- they've just randomly sent out thousands of emails to different email formats. Imagine your email was marysmith@gmail.com, then a spammer might send emails to marysmith@gmail.com, mary.smith@gmail.com, mary_smith@gmail.com, marysmith1@gmail.com, mary.smith1@gmail.com and so on.


Sometimes you might receive phone calls intended for someone else. This could be because someone who is in debt has just supplied a random phone number to get the debt collectors off their back. Less likely is that someone in the past had the number that has been allocated to your SIM Card and hasn't updated businesses with their new mobile number. 


Unfortunately there's nothing we can do to prevent phone calls from telemarketers or phone calls intended for someone else. 


Did you know you can BLOCK incoming calls from particular numbers?  So if you've been receiving wrong number calls or texts 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".