March 14 : Mobile number portability is useful when switching from one service provider to another; and when switching from one location to another, which could be problematic if the original service provider does not have a footprint in the area to which the subscriber proposes to move.

A number of technical and cost sharing problems need to be sorted out before introducing mobile number portability between one service provider and another.

Which is why we will need to wait at least another year. `Off-switch' solutions involve store all or ported mobile numbers in centralised external databases that all network switches can query when trying to reach the dialled number. Alternatively, distributed or multiple external data bases could be set up with, say, each separate data base comprising only all or ported numbers from a particular service provider.

A consortium of network operators would be required to manage/coordinate such databases, unless the task is outsourced to a third party. In the case of internal databases, call forwarding, in which incoming calls are directly routed by the old to the new service provider on an ongoing basis, is the simplest. The more complex, but for the service provider more hassle-free, method is `call drop back' under which a service provider responds to incoming calls by simply providing feedback that allows the originator to reroute calls to the new service provider.

To design efficient, simple, secure and practical porting procedures, issues that need to be addressed include: change and costs of change of SIM cards and/or handsets, authenticating the identity of customers requesting a port, communication arrangements between service providers during porting, and procedures for handling a large number of porting requests in a reasonable time.

Costs involved

Three sorts of costs are associated with the introduction of mobile number portability: system set-up costs, costs of conveyance of calls to ported numbers, and administration costs such as those incurred in closing/opening accounts and coordination between service providers in switching over of mobile numbers and routing calls.

The TRAI Consultation Paper 7/2005 concludes with two additional points: (a) Users find it desirable to predict the price of calls, and porting numbers should not undermine this capability. While costs may change, predictability of costs should not. One suggestion thrown out by TRAI (Telecom Regulatory Authority of India), for what it is worth, is that `tariff transparency can be achieved by the use of recorded announcements at the start of each call.'