Supplementary services

Date: 2015-10-07; view: 415.

Supplementary services are provided by means of enhancements to the basic call processing software in the MSCs. Many of these services have specific relevance to the cellular radio user, and in the main they parallel services which are becoming increasingly avail­able on the fixed telephone networks (such as BT's Star Services in the UK). Typical services are as follows:

1. Call divert, where all calls are diverted to the specified number, which may be another mobile or a termination on another network. This is of use if the user wishes to make calls but not receive them.

2. Divert on no answer, where calls are diverted to the specified number when the user does not answer within (for instance) 20 seconds. This is of use if a mobile is left switched on in an unattended vehicle.

3. Divert on mobile unavailable, where calls are diverted to the specified number if the network cannot contact the mobile owing to its being turned off or out of range. This is of particular use in a cellular system where, in general, users are not avail­ able at all times, and where coverage is not universal. This service is often combined with the "divert on no answer" service.

4. Divert on busy, where calls are diverted to the specified number when the mobile is already engaged on a call. As an alternative, networks also provide call waiting.

5. Call waiting, where if a call is received when the mobile is already engaged on a call, the user is informed that a second call is waiting, and can choose to place the first call on hold whilst dealing with the second caller.

6. Three party calling, where the mobile user may set up calls to two other parties and connect them in a three way conference. This service can also be used to make enquiry calls whilst holding the original call.