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Wireless carriers dream of the day when wireless phones will be considered just phones, and that the decision on whether to purchase a wireless phone in addition to a landline phone will change into a decision on whether to purchase a wireless phone instead of a landline phone. What are the factors that stop all but the bravest of people from making this decision today? Is it an issue of radio technology, or are there some backside network issues as well?
The simplest method for wireline replacement is to use a radio link instead of a copper wire for the connection between a standard landline phone and the telephone switch. This concept, known as wireless local loop (WLL), does not enhance the services provided to a current wireline customer, but merely offers an alternative method of connection to the carrier. The difficulty with this approach is getting the cost of the wireless connection down to the cost of a copper loop. Obviously, the farther a customer is from the switch site, the more likely this will be achieved. Wireless local loop is therefore a most viable alternative in rural areas and in underdeveloped countries.
While customers of wireless local loop gain no additional services, they may have trouble with data services. Most digital wireless access methods are optimized for transmission of the human voice, and can use low bit rates, such as 8kbps or even 4kbps. The lower bit rates (as compared to the 32kbps or 56kbps used in wireline networks) reduce costs by allowing more people to share the same equipment. The highly sophisticated voice coders needed to achieve this compression will generally seriously damage modem tones. Even if modems could be used over these links, they could only achieve higher speeds than the voice coder rate by recognizing an attempted data transmission and allocating more bandwidth. Recognizing modem tones is error prone, and would increase the cost and complexity of the wireless local loop interface.
Another approach to wireline replacement is to simply use a standard wireless phone, to try to take advantage of some of the capabilities of wireless, such as mobility. The same phone can be used whether the customer is in their home or office or possibly even out at the cottage or on the ski slopes. There are many reasons why people may find problems with this approach. One is that high speed internet access is not going to be possible, which would force people that need this into keeping their fixed connection. But another limitation, that is less well known, is the lack of operator services. Today it is not possible to call a wireless phone collect, to third-party bill a call or to call person-to-person. While these services are not used very often by most people, they can be very important. Anybody with children, for example, would want them to be able to call home if they have access only to a payphone even if they do not have coins or a phone card in their pocket.
Landline telephone companies provide operator services through a network of databases and the use of billing record standards that are not currently accessible to wireless carriers. The databases are known as LIDB (Line Information Database), and allow one carrier to determine whether a line controlled by another carrier is eligible for receiving a collect call or for third party billing (for example). When the call is over, a billing record is generated in the EMI/EMR format, which can be exchanged with the carrier that is responsible for the billing. On a regular basis, wireline carriers settle the monetary differences that result from this billing among themselves.
Wireless carriers are hermetically sealed from this process. They do not maintain LIDB systems, and use the CIBER format for the exchange of billing records. Establishing LIDB systems would be a major investment on the part of wireless carriers. Even if a LIDB interface was simply added to existing HLRs, this would represent considerable software development and probably a need for hardware upgrades (memory and disk at least). Converting CIBER records to EMI/EMR (and vice-versa) would require a significant industry effort to determine the appropriate mapping, followed by the development of gateways. Furthermore, the landline carriers would have to open up the settlement ‘pot’ for operator assisted calls to the wireline industry. Wireless carriers will have to push long and hard before they can make any progress, and right now they do not even see it as an issue.
There is a third approach to wireline replacement that is intriguing, although it has not yet taken the world by storm. TIA standards committee TR-45.1, responsible for the development of analog cellular standards, has developed a system that allows a wireline phone connection to be enhanced with cordless and cellular capabilities. One major part of this system is a base station that could be installed in a home to provide cordless-like coverage within the home, but using low powered cellular frequencies instead of cordless frequencies. Operating like a cordless phone, it would provide unlimited free calling within the range of the base station. The other major part of this system (defined in TIA/EIA/IS-680) is a signaling protocol between the base station and the supporting wireless system, which runs over the landline phone connection. Whenever the modified cellular phone detects its home base station, it registers, and the base station will then use the phone line to tell the wireless system that the mobile was present. Now, when any calls are made to the mobile’s phone number, the call will be diverted to the home phone line. Similarly, when the mobile phone moves outside the coverage area of the home base station it will register in the public base station with the strongest signal, and calls will be delivered to it in the same way as for other wireless phones.
Wireline replacement can mean different things to different people. There is little question that wireless technologies will continually nibble away at the market share of wireline phones. However, there are substantial issues that have not yet been seriously tackled. When wireless carriers start fighting for access to wireline networks and databases, you will know that a new phase in the struggle for dominance has begun.
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