This paper describes the implementation of a technique for integrating paging systems with the Internet through electronic mail.
Just as the Internet has become a major component of the IT industry today, another industry that has gained in popularity in recent times is paging. In spite of the rapid growth of more sophisticated mobile communications services such as cellular, the demand for this simple, one-way communications service is constantly on the rise. Its users range from doctors to businessmen to housewives.
The growth of the Internet and that of the paging industry has been independent, with different communities being served by each. However, if a pager is capable of accessing even a part of the resources on the Internet, it would undoubtedly enhance its value several-fold. With the technique described in the paper, not only will the pager be part of a global network, but it will also be achieved with no additional infrastructure. It will extend the reach of the Internet as well, to an entirely new community which would benefit greatly by the connectivity provided by this low-cost link.
In Sri Lanka, e-mail is currently provided predominantly as a dial-up service, where subscribers dial up the service provider's host computer periodically to transfer messages. Paging systems in general also provide dial-up access to a computer at the paging controller. Our technique makes use of this facility. As soon as a message for a pager is received by the host, it will dial-up the paging controller and send a notifying message to the appropriate pager.
The design of the system consists of two main software components at the e-mail host computer and at the paging controller and another module for communication between these two computers.
The module at the e-mail host detects messages received for pagers, and transmits either the entire message, or a notification with the sender and the subject to the pager. The communication module is based on a protocol where the e-mail host logs into the pager controller with a pre-assigned login name and a password and the destination pager number. After the authenticity of these is verified, the paging message is transmitted by the e-mail host. The module at the pager controller extracts this message from the incoming data and forwards it to the transmitter for broadcasting through its network. The communication is carried out using asynchronous modems at both ends.
Advantages and Disadvantages
The main advantage of this technique is that it adds value to paging systems by extending its accessibility to the global community of the Internet.
Another is that immediate notification of the reception of an e-mail message is made possible without a dedicated connection to the host, which may be expensive and unavailable. Notification of a message is sent immediately on reception, and the subscriber can retrieve it in the normal manner by dialling up the e-mail host at his convenience. Hence, this technique can be used to supplement a regular e-mail service. It may also be possible to send the entire message to the pager as soon as it is received, in which case, this can be used as a stand-alone system.
The mobility provided by the pager is another advantage. A subscriber who is constantly on the move can use this technique to supplement his e-mail access without incurring the expense of a wireless modem or a radio mail system.
The shortcomings of this technique are mostly due to the bandwidth restrictions and the one-way nature of paging systems.
Currently, paging systems operate at 512 b/s. Hence, sending a long e-mail message may unduly overload the system. In this case, an alerting message could be sent, and the actual message transmitted at a time when the traffic on the paging network is low.
Another disadvantage is that the pager receiver, not being equipped with a transmitter, has no way of originating e-mail messages, or even acknowledging the reception of one.
The limited memory capacity of a pager receiver may not be sufficient for storage of messages for later retrieval. For this, the paper proposes an interface between the paging receiver and a personal computer through which the messages may be transferred to the computer for storage.