Making a call to a local or international number via calling cards is just about the most commonplace phenomenon today. However, do you know what technology goes into these calling cards? Of the two principal technologies used in called cards, stored value and remote memory, the former is utilised in prepaid phone cards, which is the most popularly used phone card around the world. SIDA, a European telecommunications company made the first calling card systems in the mid 1970s, but it would take another decade for these phone cards to reach users in the US, and around the world.

A pre stored value phone card of the earliest calling cards employed a magnetic stripe to encode information, similar to key card or ATM technology. Some years later came the optical storage technology, which were more sophisticated than the magnetic coding used earlier. Optical telephone cards had physical readers on the cards like lines or holes, which the card reader would scan for balance information. Optical calling cards were widely used by many users around the world. Optical phone cards utilised relatively simple technology, so the disadvantage was that these could very easily be hacked. Due to these security concerns, the optical calling card was slowly being phased out from countries around the world.

By the next decade, a new technology was to find implementation in the calling card system, which was the chip technology. First manufactured by the Deutsche Bundespost in Germany in 1986, these chip stored value phone cards quickly became the norm when it came to calling card technology for the next few decades. Although initial concerns were the easy to scratch off programming voltage point in the card causing a security breach, later technology was much more reliable. With modifications to this primary chip card technology, today's calling cards using microchips are not easily hackable, with the addition of secure coding technology.

The other technology used apart from the stored value system, is the remote memory system. This involves a central database, which supplies information about balance, which the card registers through an access number. The company Phone Line launched the first ever, remote memory calling card in United States in 1980. These phone cards could typically be used from any phone with tone mode facility. This definitely was a boost for users because there were telephone cards around that required special card readers along with the phone. The only disadvantage that this type of card professes is the keying of many digits before you can actually make a call. International remote memory calling cards required the caller to dial three different numbers before the call could be connected, an error in any one of which would not allow the call to get through. This process was certainly a very laborious one for the user, and this was the major disadvantage of such a calling card.

Today's mobile phone or landline user can enjoy many benefits on their calling cards. Depending on the telecommunications service provider of such calling cards, the user can pick networks within which to operate, thus allowing for discounted rates as well as superior coverage.