Addresses to Lines Assignments

An address is the telephone number, complete with national or international codes, of a telephone, fax machine, or other device that can receive calls. Addresses can be dialed by a human or stored in an electronic directory for retrieval and use by a telephony application. For more complete information on addresses assignments, channels, and lines, see Line Devices Overview.

The local assignment of an address to a line (that is controlled in TAPI) takes place in the setup operation for the service provider. This can be done using the Control Panel to configure the service provider or by calling the lineConfigDialog function from within the application. On the local side of the central office, everything about a line is controlled by a service provider, such as whether there are multiple addresses and what these addresses are.

Usually, there is exactly one address per line, with the following exceptions:

  • Multiple Addresses with POTS. In POTS, multiple addresses work only with systems that support distinctive ringing or are connected to a DID trunk. (DIDpics/TAPI00090000.gifdirect inward dialingpics/TAPI00090000.gifis an extra-fee service provided by the phone company.) With DID in a multi-user voice mail system, the dialed number is signaled to the system on the DID trunk before the call rings. This allows the system to play the called party's pre-stored announcement message and to store any incoming messages in the correct voice mail box.

On a residential line with distinctive ringing service, different ringing patterns correspond to multiple numbers assigned to the same line.

  • Multiple Addresses with ISDN. ISDN was designed to allow simultaneous multiple addresses by providing multiple channels, each of which can have its own address. On an ISDN network, call offering (which means a call-setup message has been sent from the switch) takes place before ringing, so the call can be redirected before it is answered. The lineAccept function means start ringing for ISDN. For POTS, it means that some application has accepted responsibility for the call and has presented it to the user.

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