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The Wireless Number Portability (WNP) implementation deadline is looming ever closer for wireless carriers. The November 2002 date is unlikely to be moved unless courts rule against it, the US FCC has a complete change of heart or some major problems erupt in landline number portability.
The landline number portability mandate (LNP) already requires wireless carriers to perform queries to a Number Portability Database (NPDB) to route calls to ported landline phone numbers in major metropolitan areas. The November 2002 deadline will allow wireless numbers also to be ported, either to or from another wireless carrier or a landline carrier. The major change required by this phase of number portability is the separation of the MIN and Mobile Directory Number (MDN) to allow wireless systems to identify the true home carrier at the time of registration. Every wireless phone that is ported to another carrier will have an MDN that is unchanged (and appears to point to the old serving carrier – only the NPDB can tell for sure) and a MIN (or IMSI) that has been reprogrammed to point to the HLR of the new serving wireless carrier.
The challenge of WNP for wireless has increased substantially because of another mandate – Number Pooling. This uses the WNP infrastructure, but for a totally different purpose. The LNP mandate is intended to increase competition by allowing (largely landline) consumers to obtain service from a competitive carrier without the barrier of changing their phone number. Pooling, however, is intended to increase the efficiency of phone number usage. It does this by peeling off blocks of 1,000 numbers from under-utilized blocks of 10,000 assigned to one carrier. Because routing is to these larger blocks, the entire group of 1,000 numbers has to be ported in one operation. In fact, it is worse than this. A few of the 1,000 numbers may already be in use (a so-called ‘contaminated block’) and they must be immediately ported back to the original carrier.
Theoretically, pooling can be accomplished using the LNP infrastructure. However, pooling radically increases the number of numbers that are ported at one time, and makes number portability databases larger and more cumbersome. Queries now not just have to ask “Is this number ported? If not, I’ll take the default routing.” Now the question is “Is this number ported? If not, is it within a block of 1,000 pooled numbers? If not, default routing will apply.” To combat this change in size of the ported blocks, the NPAC (Number Portability Administration Center) has to reorganize their databases with EDR (Efficient Data Representation).
Real-time porting operations are complicated enough, but the real challenge occurs behind the scenes, when a customer attempts to port one or more numbers. When a customer is persuaded to port their phone to another carrier, the service order entry system has to initiate a local service request (LSR) to the old serving carrier. This carrier has the choice of accepting it or challenging it (if it suspects, for example, that ‘slamming’ is occurring). If the port request is accepted, the new service provider must inform the NPAC when the port is scheduled to occur. The NPAC will then download the porting information to the Local Service Management Systems (LSMS) that are used by carriers to provision the real-time NPDBs. To make matters more complicated, while this one number is being ported, it is possible that the block of 1,000 numbers that its phone number resides in is being pooled.
While carriers are planning for these radical changes to their operational and back-office networks, it is still questionable whether it is beneficial to apply the LNP or Pooling mandates to wireless. Given the high levels of churn in the wireless industry, and establishment of at least 3 competitors in most markets, it is hard to believe that changing phone numbers has been much of a barrier. Wireless consumers do not suffer as much when changing phone numbers because their number is generally not in a phone directory, and usually is known by relatively few people.
The LNP mandate cannot guarantee that the porting process will be smooth for the consumer in practice. Often, when changing between digital systems, a new phone will need to be purchased or a long-term contract purchased. MIN reprogramming will also need to be done. Further, 911 callback may not be possible when ported phones are in an area outside the LNP mandate, because these systems may retain the current assumption that the MIN is the same as the MDN.
Nobody questions the need for number conservation, but the question is whether Number Pooling is the best approach. The basic problem appears to be that rate centers, the fundamental billing and routing unit in the North American Number Plan, are too small in many cities. Consolidating rate centers allows carriers to distribute one block of numbers to all customers within this larger area, making it possible to use numbers that were previously stranded in a rate center with low growth. This could be much more beneficial than pooling, but requires action at the state level, and could reduce intra-LATA long distance revenue to incumbent local exchange carriers.
Wireless carriers are likely to continue to fight against the WNP and Number Pooling mandates. However, they must also plan to implement the mandates because there is no guarantee that any more extensions will be granted, let alone that they will be granted an exemption from them.
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