Legacy Narrowband Services
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Network modernization without sacrificing legacy copper-based services

Service provider networks are evolving to take advantage of new technologies that support users’ insatiable demand for bandwidth. But change does not happen overnight, and legacy telecom services continue to remain an important part of network operations. In many cases, large and small businesses have made big investments in legacy equipment and related processes. When the companies expand to new locations, or add capacity, it often makes sense to continue deploying embedded technologies, and in some cases, government tariffs regulate that service providers must offer services that fall into the “legacy” category.

Tellabs Broadband products are well suited to meet the demands of all services in today’s networks with a clear path to evolving services. Tellabs is the industry’s only telecom equipment provider that supports service providers’ needs for all legacy services while simultaneously providing emerging services. The Tellabs Broadband product line offers many legacy analog interfaces that support Plain Old Telephone Service (POTS) two and four-wire switched and non-switched services. Examples of services include ISDN, Coin, DID/DOD, FXS/FXO, as well as support for Centrex and PBX.

Quick Facts


  • Modern optical and Ethernet connectivity at central office, remote cabinet or customer premises support side-by-side with traditional copper-based TDM.


  • Legacy POTS, TR-57, GR-303, TR-008 circuits supported.


  • Industry-leading analog special services delivery.



  • Ethernet, ATM and TDM interworking across the Tellabs 1000 MSAP.


  • Many T1 configurations and applications supported.


  • ISDN, HDSL and DDS plug-in cards available.


Traditional narrowband support options


Legacy telecom services continue to be an important part of how service providers deliver voice and digital services to customers. Tellabs Broadband products provide ongoing support for legacy services while providing a path for transitioning to newer technologies.


Plain Old Telephone Service (POTS)


The cornerstone of many networks is POTS. The Tellabs 1000 MSA) provides POTS to residential and business subscribers in the access network and interface to the Public Switched Telephone Network (PSTN). The Tellabs 1000 MSAP can interface with all Class 5 switches and supports all three standard interface types deployed in North America: universal with GR-57, and integrated with GR-08 and GR-303. The Tellabs 1000 MSAP is also extremely scalable. A system can be deployed as a single shelf with one to 100 subscribers, or it can be up to 32 connected terminals in various topologies with up to eight shelves each, providing service for up to 2,000 subscribers.


GR-303 interfaces support


The primary benefits of the Tellabs 1000 GR-303 interface include reduced costs for equipment, maintenance, and inventory, and no need for L-POTS, L-PAY, L-UVG or L-ISDN plug-in cards. There are reduced costs through efficient use of switch ports, increased revenue through greater subscriber concentration and dynamic time slot interchange and higher quality of service because of the digital interface, including increased modem speeds. Tellabs GR-303 solution delivers the following capabilities such as up to three interface groups per Tellabs 1000 MSAP system, from 2 to 28 DS-1s per interface group, up to 28 total DS-1s per Tellabs 1000 MSAP system, up to 2,048 CRVs per interface group; up to 2,048 total CRVs per Tellabs 1000 system at a 3:1 concentration and up to 672 subscribers off-hook simultaneously. There is support for up to 32 remote terminals per LET or master terminal and support for 4:1 ISDN D-channel multiplexing. Excellent scalability is achieved with the Tellabs 1000 MSAP supporting up to 2,000 off-hook lines of POTS services without consuming narrowband DS-0s on the terminal’s primary shelf.


Special services


Analog special services continue to be deployed. The Tellabs 1000 MSAP is the only, DLC available that can provide a full range of services. The following list provides examples of the analog special services; Direct Inward Dial Service (DID), Direct Outward Dial Service (DOD), 2- or 4-wire E&M Service usually used in the central office Equalized Transmission Only (ETO), Foreign Exchange service applications (FXO/FXS), Voice private line services (Leased line) — Analog, non-switched, 2- or 4-wire service, Off-premises extension — Analog 2-wire, Off-premises PBX — Analog 2-wire, PBX — Local PBX trunk service and Private Line Automatic Ringdown “hotline” service (PLAR).

T1 lines


The Tellabs 1000 MSAP offers multiple T1 options to provide services and network transport, including T1A modules for full 1.5 Mbps services (with and without line powering options), channelized T1 modules, supporting access to the individual 64 Kbps channels (with and without line powering options) along with HDSL2 (2-wire HDSL) and HDSL4 (4-wire HDSL) modules. The Tellabs 1000 MSAP has options for asynchronous service, also known as intact service, and provides a T1 interface to the terminating equipment where the entire 1.544 Mbps is used for customer payload. There are also options for non-line powering T1 plug-in cards as well.


High-bit-rate Digital Subscriber Line (HDSL)


The T1 HDSL2 Transceiver (T1HD2-XCVR) plug-in card provides a T1 rate interface, transmitting and receiving up to 24 DS-0s of voice or data over one copper wire pair. The T1HD2-XCVR does not use separate transmit and receive pairs. Instead, it uses one pair that provides bidirectional transmission. The card can function in an unframed format to allow for intact (asynchronous) T1 delivery to subscribers. It can also function in a framed format to deliver groomed T1 service. The T1HD2-XCVR card provides a single T1 rate interface up to 12 kft over nonrepeatered 24 AWG copper facilities or 23 kft over repeatered 24 AWG copper facilities. The T1 HDSL4 Transceiver (T1HD4-XCVR) plug-in card provides a T1 rate interface, transmitting and receiving up to 24 DS-0s of voice or data over two copper wire pairs. The card uses two copper wire pairs, each running at half the HDSL4 data rate. Each copper wire pair provides bidirectional transmission. The T1HD4-XCVR card can function in an unframed format to allow for intact (asynchronous) T1 delivery to subscribers.


Integrated Services Digital Network (ISDN)


Integrated Services Digital Network (ISDN) is a standard technology that supports many services, including radio circuits, business-to-business intranetwork connections and legacy DDS. Tellabs provides the capability to provide ISDN in switched networks in both universal and integrated switch interface configurations.


Digital Data Service (DDS)


Legacy DDS provides functionality in applications that need only relatively low bit rates. There’s no reason to blast large amounts of data and capacity at a function when only a small amount is required. Examples of the functions/services include bank ATM machines, retail store scanners and lottery machines. The legacy DDS capability in the Tellabs 1000 MSAP product line is centered on the OCU-DP and DS-0 DP modules. These line cards support the standard DDS (Digital Data Service) of 2.4 Kbps, 4.8 Kbps, 9.6 Kbps and 64 Kbps services.


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