TAP actually has multiple names. TAP, IXO and PET all refer to the exact same protocol.
TAP/IXO is an industry standard message delivery protocol for analog modems,
or direct serial communications to wireless
and telecom providers.
Using the TAP protocol messages are sent from a computer using a modem and software. When the modem connects to the terminal, the software communicates with the terminal in a fashion that the terminal understands (using the TAP protocol0> The terminal then broadcasts the message to the appropriate wireless device or mobile phone.
In order to send a message a message using TAP, two pieces of information are required. The first required piece of information is the TAP Terminal Phone Number and the second is the pager ID or mobile phone number you wish to send the message to.