Just as the line device component ThbTapiLine is an abstraction of a physical line device, the phone component ThbTapiPhone represents a device-independent abstraction of a telephone set. TAPI treats line and phone devices as devices that are independent of each other. In other words, you can use a phone (device) without using an associated line, and you can use a line (device) without using a phone.

A phone device is a device that includes some or all of the following elements:

Hookswitch Devices

A phone device can have multiple hookswitch devices. A hookswitch is the switch that connects or disconnects a device from the phone line. On a telephone, for example, this is the switch that is automatically activated when a user lifts the receiver from the cradle to get a new dial tone.

TAPI defines three types of hookswitch devices for a phone: handset, speakerphone, and headset. Each hookswitch device has a speaker and a microphone component, and operates in one of four hookswitch modes:

Display

TAPI provides access to a phone's display. The display is modeled as an alphanumeric area with rows and columns. A phone's device capabilities indicate the size of a phone's display as the number of rows and the number of columns. Both these numbers are zero if the phone device does not have a display. Use the Display.Text property to to write information to the display of an open phone device and to retrieve the current contents of a phone's display.

When the display of a phone device is changed, a OnDisplay event is fired to notify the application about the state change.

Ringer

A single phone may be able to ring with different ring modes. Given the wide variety of ring modes available, ring modes are identified by means of their ring mode number. A ring mode number ranges from zero to the number of available ring modes minus one.

Use the Ringer property to control a phone device's ring mode and volume. When the ring mode/volume of a phone device is changed, the OnRingMode/OnRingVolume event is called to notify the application about the state change.

Phone Buttons / Lamps

TAPI models a phone's buttons and lamps as button-lamp pairs. A button with no lamp next to it or a lamp with no button is specified using a "dummy" indicator for the missing lamp or button. A button with multiple lamps is modeled by using multiple button-lamp pairs.

The lamps on a phone device can be lit in a variety of different lighting modes. Unlike ringing patterns, lamp modes are more uniform across phone sets of different vendors. A common set of lamp modes is defined by the API. A lamp identified by its lamp-button identifier can be lit in a given lamp mode. A lamp can also be queried for its current lamp mode.

Use the ThbTapiPhone.Controls property to control the buttons and lamps. When the state of a phone's button/lamp is changed, the OnButton/OnLamp event is called to notify the application about the state change.