PINT Services

The basic PSTN/Internet Internetworking (PINT) services (RFC 2458) include click-to-dial-back, click-to-fax, click-to-fax-back, and voice-access-to-content. The common denominator of PINT services is that they combine the Internet applications and PSTN telecommunications services in such a way that Internet applications can request the PSTN telecommunications services. Further, the Internet is used for nonvoice interactions, while voice (and fax) is carried entirely over the PSTN. An example of such a service is the combination of a Web-based Yellow Pages service with the ability to initiate a PSTN call between a customer and a supplier in the manner described later. Note that the word click in some of these services should not be taken literally and construed as a prescribed way for invoking the services. It is rather used to underline that service initiation takes place on the Internet, where pointing and clicking are the most prevalent user actions.

Click-to-Dial-Back
With the click-to-dial-back service, a user requests (through an IP host) that the PSTN call be established with another party. As in several other examples of PSTN/Internet hybrid services, an important prerequisite for using this service is that the user have both voice access to the PSTN (via a telephone terminal) and data access to the Internet (via a PC).

A typical example application of this service is online shopping: A user browsing through an online catalog clicks a button, thus inviting a call from a sales representative. Note that (as is the case with the all-PSTN freephone), flexible billing arrangements can be implemented on behalf of the service provider. In addition, the PSTN can route the call depending on the time of day, day of week, availability of agents in different locations, and so on.

Click-to-Fax
With click-to-fax service, a user at an IP host requests that a fax be sent to a particular fax number. This service is especially meaningful when the fax is to be sent to someone who has only a fax machine but no access to the Internet. Consider as an example a service scenario in which a Web user makes a reservation for a hotel room in Beijing from a travel service page containing hotel information for major cities around the world. Suppose a specific Beijing hotel chosen by the user does not have an Internet connection but has a fax machine. The user fills out the hotel reservation form and then clicks a button to send the form to the service provider, whose equipment then generates a fax request and sends it together with the hotel reservation form to a PSTN node. Upon receiving the request and the associated data, the PSTN translates the data into the proper fax format and delivers it to the Beijing hotel.

Click-to-Fax-Back
With click-to-fax-back service, a user at an IP host can request that a fax be sent to him or her. Now the traveler of the previous example can request confirmation from the Beijing hotel. Another useful application of the service is when the size of the information that a user needs to retrieve is so large that downloading it to the user’s PC over the Internet would require a long time and too much disk space.

Voice-Access-to-Content
With voice-access-to-content service, a user at an IP host requests that certain information on the Internet be accessible (and delivered) in an audio form over the PSTN, using the telephone as an informational appliance. One application of this service is providing Web access to the blind. (This may require special resources—available in the PSTN—to convert the Web data into speech.) A variant of this service is that the telephone is used to initiate as well as to retrieve the content. In other words, the user requests through the telephone with voice commands that certain information on the Internet be delivered in an audio form over the PSTN and heard on the telephone.