Internet Call-Waiting

Call-waiting is a familiar service in the PSTN world. With this service, a subscriber who participates in a telephone call is notified when another call comes in over the same telephone line. Then it is up to the subscriber to place the party on hold and accept the incoming call, or to ignore the incoming call. After accepting the new call, the subscriber can also toggle between the two calls.

As the number of data calls grew, the telephone companies realized that they needed to provide the means for temporarily disabling call-waiting. Subscribers invariably use the cancel waiting feature when they go on-line; if they did not, the tones that indicate the arrival of a new call would interfere with the operation of the modem and could result in loss of the connection. Until the Internet call-waiting (ICW) service was introduced, subscribers could not eat their cake and have it, too.

The ICW service typically works as follows:

§  When the subscriber logs onto the Internet via a dial-up connection, the IP address of his or her PC is recorded.

§  When the network detects an incoming call destined to the subscriber, a dialog box pops up on the subscriber’s screen. The dialog box presents the caller’s telephone number or name, if available, and a set of options for call treatment. The options may include the following: accept as an IP voice call, accept as a PSTN voice call, route to another telephone number, or route to voice mail.

§  After obtaining the subscriber’s response, the network implements the option chosen.

Unlike its PSTN counterpart, the ICW service does not always support toggling between the calls. In the case where the incoming call is accepted as an IP voice call, toggling between calls is just toggling between applications, which makes it simple to support. But the case where the incoming call is accepted as a PSTN voice call, toggling between the PSTN call and the data call is not currently supported.

The ICW service can be enriched with many useful features. For example, the subscriber may be given the option of setting up a list of telephone numbers from which all originating calls are to be blocked, keeping a log of calls not answered, and returning calls by automatic dial-out. In addition, the idea behind the ICW automatically extends to “Internetization” of a large set of IN-supported services (such as call-forwarding, personal number, or follow-me).

It is obvious how the ICW service benefits Internet users. It also benefits service providers by increasing the number of completed calls.