The history of the prepaid mobile phone begins in the 1990s, when larger markets were being sought after by the . Before this date, all mobile phone services were offered on a , which excluded people with a poor .
In the early years, prepaid mobile phones could only be used within the network from whom the customer purchased the phone. It was not possible to onto other GSM networks when using the phone abroad. This was because the operator had no way to bill calls in real time from another network.
There is no compulsion on a prepay mobile phone user to top up their balance. To maintain revenues, some operators have devised reward schemes designed to encourage frequent top-ups. For example, an operator may offer some free SMS to use next month if a user tops up by a certain amount this month.
Credit purchased for a prepay mobile phone may have a time limit – for example, 120 days from the date the last credit was added. In these cases, customers who do not add more credit before expiration will have their remaining balance depleted through expiration of the said credits.