16.6 Service Models by Carriers

In addition to the general requirement for the VoDSL loop extension CPE listed above, the specific service model used by the carrier to provide VoDSL will effect the requirements for the CPE. Five potential service models that could be developed using loop extension over DSL are discussed. These five models are examples of how voice service might be offered over DSL by a carrier. Detailed requirements for CPE would of course be based on the specific filed requirements of carriers actually offering VoDSL loop extension services.

Residential Supplemental Lines . In this service model, the DSL access is used to provide additional voice lines as a relatively low-cost add-on to the DSL data service. The carrier offers low cost supplemental voice lines and does not attempt to replace the existing life line service provided by the ILEC with VoDSL provided lines. There may be no coordination between these supplemental lines and the existing lifeline service. These lines might be installed to serve a home office. Although the voice and service quality are similar to those for conventional analog POTS, no attempt is made to provide the same level of reliability. Instead the service is marketed as a low-cost enhancement bundled to a DSL data service. It is most likely that a CLEC would offer such a service to gain extra revenue from a residential data service. Requirements of CPE (customer premises equipment) supporting such a service model might include:
1. Support for two to four derived POTS lines.
2. CPE is placed on the user 's desktop.
3. POTS interface integrated into DSL modem.
4. No power backup requirements.
5. Possible fail-over of supplemental extensions to the analog life line in case of power failure at modem.
6. Possible end-user self-installation.
Residential Full Service Replacement . In this service model, the carrier provides all of the home voice services using VoDSL. No analog life line service is provided. Instead the VoDSL equipment and network are designed to provide the reliability required for life line service to a home. The user's existing POTS home wiring and telephones continue to be used, and the existing connections to the analog NID are moved over the new VoDSL interworking device when this service is installed. This service is likely to be provided by a CLEC or IXC attempting to compete directly with the Incumbent Carrier. CPE requirements for this service might include:
1. Support for two to four derived POTS lines.
2. CPE is placed at the NID (network interface device ”the entrance to the home), either inside or outside the home.
3. CPE is protected against power failure with battery backup or a very-low-bandwidth line powered DSL backup mode.
4. CPE meets network equipment levels of reliability.
5. Data service is extended over Ethernet or Home LAN technology from NID location to various sites in home.
6. CPE installed by carrier or service provider.
Residential Full-Service Replacement Integrated with Existing Analog Service . In this service model, the carrier provides additional voice lines using VoDSL, while the analog POTS service is maintained to support life line service. The analog and VoDSL supported lines are provided as an integrated service and are likely supported from the same class 5 switch. The ADSL service is carried on the same loop as the analog voice. In case of power failure, the extensions supported by VoDSL may be automatically switched to be served by the analog line. This service model may be attractive to an ILEC, especially to support homes that are currently served by pair gain technologies such as DAML. CPE requirements for this service might include:
1. Support for 2 to 4 derived voice lines.
2. CPE is placed at the NID, either inside of outside the home.
3. All lines fail over to analog line in case of power failure.
4. ADSL Splitter is integrated into CPE.
5. Data Service is extended over Ethernet or Home LAN technology from NID location to various sites within the home.
6. CPE is installed by carrier or service provider.
POTS Replacement to Small Business . In this service model, the carrier provides all of the small business voice services using VoDSL. Analog life line service is not necessarily provided, as CPE can be provided with batter backup or a UPS in a business environment. The user's existing POTS premises wiring, telephones, and PBXs continue to be used. The existing connections to the analog NID are moved over the new VoDSL interworking device when this service is installed. A CLEC, IXC, or ILEC might provide this service. CPE requirements for this service might include:
1. Support for four to sixteen POTS interfaces.
2. CPE placed in wiring closet.
3. Battery backup or UPS.
4. Optional support for an analog backup line.
5. Data service extended into premises over 10/100 BaseT Ethernet.
6. Network equipment level of reliability.
7. CPE installed by carrier.
Micro-DLC . In this service model, the loop provider emulates multiple voice lines by placing a network-owned VoDSL unit on the line before the line enters the customer's premises. The customer-end unit is powered from the CO via a DC voltage applied to the line by VoDSL equipment at the CO. The VoDSL units at both ends of the line multiplex data and multiple digitized voice channels into the DSL payload. Multiple separate voice lines are provided at the demarcation point to the customer.
1. Support for two to four POTS interfaces.
2. Customer-end unit placed outside the customer's premises.
3. Equipment powered by line-fed power from CO.
4. No battery backup needed.
5. No baseband analog voice transmission.
6. Optional data service extended into premises using HomePNA (home phone network alliance) or wireless LAN.
7. Installed by carrier.

Top