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The various aspects of number portability are likely to be solved in stages by separate measures. They include:
- local number portability between carriers
- portability of analogue and ISDN numbers to adjacent or distant geographic areas, perhaps with a different carrier
- the ability to change from one GSM carrier to another and retain the same number
- the ability of a business with an assigned and well known national free-call number, such as 13 10 65 - that is currently part of one carrier's number range - to change to an alternative carrier and retain the same number
The 'Simple Intelligent Network' Solution
There is a 'simple' solution, based on SS7 and in keeping with the vision of the entire telephone network being a truly 'Intelligent Network'. Whenever a number is dialed, the originating exchange performs a database lookup on that number to determine which carrier services it, and at what point the originating carrier's network should take the call to before passing it over to the destination carrier.
Every time an Internet computer needs to send a packet (or more likely a stream of packets) to another computer it knows by a text name, such as 'www.verizon.com', it does such a database lookup. Rather than interrogate a single central database, the Internet's DNS system is much more decentralized, with separate databases and servers for each name-space, such as 'verizon.com' or '.com'. The load on these servers is reduced by intermediate name-servers, which perform the lookup on behalf of each computer, caching the results for a defined period of time. So a particular Internet name can be made to translate into any IP address on the Internet. This architectural superiority is one of the reasons why Internet communications is flourishing at the expense of telephony.
Unfortunately such a 'database lookup' approach is difficult to apply to the existing telephone network. If exchanges were becoming obsolete and getting cheaper as fast as personal computers, then it would be a relatively simple matter to re-engineer all exchanges for greater computational and storage capacity, and beef up the SS7 network by which the communicate.
Over a decade or two, this will probably happen. At present, to require that each exchange contain an up-to-date copy of the national numbering database, or to access such a database at a remote site and retain a cache of the results of recent queries to eliminate the need to burden that remote site with repetitive queries, would be beyond the computational capabilities of existing exchanges. It is certainly well beyond the intended functionality of existing exchange software. So even if the CPU speed and memory capacities of the exchange's computers were suddenly increased by a factor of ten (which is not an unreasonable goal, considering the age of the exchange designs and the rapid progress in CPU clock-speeds) and even if the inter-CPU communication busses in the exchanges were similarly upgraded (which could be difficult or impossible) then new software would still need to be written and tested.
Assigning the Costs of Portability
None of this is impossible, but the costs of implementing such a wholesale change to the phone network, and of managing this new, portable number, multi-carrier, network are high and must be paid for by someone. The greatest costs fall on those carriers with the largest networks, and it is these companies who have the greatest number of customers to lose when number portability is achieved.
The carriers need to recover their costs from somewhere, but there is no new business in number portability - at least for the most established carriers. It is not possible to charge the cost to those who chose to use portable numbers - that would dissuade them from exercising the freedom they need for competition to flourish. The only other alternative seems equally unfair: to spread the costs over all customers, including those who do not use portable numbers. This could be justified by the direct benefit of those customers who do use portability and for the general benefit of all customers from the lower prices and better services which should be brought about by the more competitive environment which number portability facilitates.
Regulators and consumers desire that the costs of implementing portability, and of resultant lower prices overall, will come from reduced returns to carrier shareholders. Shareholders of course have a different view. Why should they spend millions of dollars complexifying their network to make it easier for existing customers to conveniently choose another carrier?
There are financial costs to be born by carriers and/or their customers. Other costs may include slower connect times for some or all calls.
Managing Number in a Portable Environment
A further set of problems arise with the management of the number range. This is a field being explored by industry and regulators in countries such as Australia, where regulators wish to prepare for full portability and to make way for multiple carriers.
There are several important implications of moving the management of phone numbers from carriers to a central, relatively independent body. One problem is maintaining the privacy of customers who choose to have ex-directory numbers - as, for instance, around 10% of Australian customers, and around half of Californians do.
Another problem is changes in the compilation of telephone directories. The White Pages directories are often seen as a service and a financial burden on the monopoly carrier, but in some cases they generate sufficient revenue from advertising, bold listings, extra listings for business, and the like to return a profit. The Yellow Pages directory market is a financial gold-mine - but only for the one company which has an up-to-date listing of all business numbers. In a single carrier environment, that carrier possesses this information, and so is the only company that can publish a truly comprehensive directory of all businesses. It is that comprehensiveness that makes it the guide preferred by users, and so which makes advertising space in such directories such a lucrative revenue stream for the publishers. Other companies without access to that up-to-date list of numbers cannot produce a comprehensive guide. The same arguments apply when the directories are made available via the Internet.
Number portability in a multi-carrier environment is a worthwhile goal, because of the increased flexibility and competition it will bring to all telephone users. It is technically and administratively costly, and the largest carriers who have the most work to do, have the least financial incentive to achieve it rapidly.
While it is true that the Internet's limited physical address range (four billion IP addresses) is a problem which must be resolve within the next five years or so, the Internet has no equivalent problem to telephony's number portability. This is because the architecture of the modern telephone system was designed in the 1930s by large, centralized, organizations using technology based on relays, and where the customer equipment was very simple, while the Internet was designed four to five decades later, by academics and researchers, with Unix computers as the customer equipment.
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