| PIN | The personal identification number is a number, which is used for access to different accounts or for making phone calls. It protects personal data. |
| Protocol | Protocols regulate the exchange of information between computers and peripheral devices. A data transmission protocol defines these rules in a type of index that contains all formats, their semantics and syntaxes, parameters and characteristics for complete, error-free, and effective data transmission. |
| PSTN | Short for Public Switched Telephone Network, this is the standard telephone service. |
