Posted: 07/15/1999
Voice Takes DSL Center Stage at SUPERCOMM
$36 Billion in Small-Biz Telephony Ripe for Picking
By Peter Lambert
Over the past year, national digital subscriber line (DSL) competitive carriers have established a model for reselling high-speed local transport to Internet service providers (ISPs), enabling the latter to offer Internet access speeds more than 100 times faster than dial-up Internet access. The model has won several DSL carriers billion-dollar valuations on Wall Street.
By this time next year, DSL competitive local exchange carriers (CLECs) also may prove a model for reselling transport to local and long distance telephone companies at costs substantially lower than traditional telephony access can offer.
DSL CLEC equipment providers threw down this gauntlet at this year's SUPERCOMM '99 convention in Atlanta, which became the forum for literally dozens of voice over DSL (VoDSL) technology partnership and field-trial announcements.
Purveyors of the new VoDSL platforms predict early deployments in late 1999, followed by an explosion of service launches in 2000. In the longer term, the capability to deliver two to 20 voice connections, along with data traveling at 128-kilobits-per-second (kbps) to 1.5-megabits-per-second (mbps) speeds--all over a single copper link--promises to turn DSL from a simple high-speed Internet access tool into a broadband, integrated access system for voice, Internet and private business data.
If successful, VoDSL could multiply DSL's revenue potential tenfold. According to Framingham, Mass.-based International Data Corp. (IDC) research, U.S. businesses with fewer than 100 employees already spend $36 billion annually on local telephone services and another $10 billion on long distance voice services, dwarfing the $3.7 billion they spend on data services.
"Now you don't have to justify DSL deployments on data alone," says Jennifer Nance Stagnaro, vice president of marketing for one VoDSL gateway maker, Santa Clara, Calif.-based CopperCom Inc. "You can justify it on data revenue, plus 10 times that much spending in voice."
A major hitch remains in the path of this scenario: The symmetric DSL (SDSL) equipment used by most CLECs does not provide network-supplied powering to phones during customer power-utility outages, meaning that VoDSL cannot reliably deliver emergency, 911 "lifeline" services.
However, the primary target for VoDSL is small to medium-sized businesses, which already use private branch exchange (PBX) phone systems that also must rely on customer-located backup generators during power outages, Stagnaro says. Further, Alcatel USA, Plano, Texas; Westell Technologies Inc., Aurora, Ill., and other providers of asymmetric DSL (ADSL) technologies--initially designed to accommodate lifeline voice plus high-speed data for consumers--also announced new partnerships and products to support lifeline circuit voice, multiline packet voice and data on a single line.
With VoDSL systems in place, advocates say, DSL packet-switched carriers will resell local, broadband transport to voice to interexchange carriers (IXCs) and CLECs with established circuit-switched telephone network facilities. The voice carriers will benefit by extending their voice network reach over single copper phone lines to small businesses in need of multiple voice connections. Alternatively, voice CLECs could be moved to roll out their own DSL facilities and take direct control of both voice and data services down to the customer premises.
"We started hearing from the so-called data CLECs a year ago that voice, particularly wholesale, would be a big part of their businesses," says Bryan Long, vice president of marketing for Copper Mountain Networks Inc., Palo Alto, Calif., a maker of DSL central office (CO) equipment, now claiming about half of the U.S. business DSL market. "VoDSL does not have to start from scratch, because it can leverage existing DSL transport, existing voice switches and existing PBXs to generate $70 per voice line, discounted to about $50, and multiplied by five to 20 lines per DSL connection."
With so much potential revenue at stake, virtually every maker of DSL CO and customer premises equipment (CPE) used the SUPERCOMM forum to announce technology integration and co-development partnerships with vendors specializing in telephone-friendly DSL customer devices and gateways that port VoDSL to the public switched telephone network (PSTN).
Among the emerging VoDSL gateway players: CopperCom; Integrated Network Corp., Bridgewater, N.J.; IPAXS Corp., Tampa, Fla.; Jetstream Communications Inc., Los Gatos, Calif.; and TollBridge Technologies Inc., Sunnyvale, Calif.
Their systems enable DSL customer equipment to accept standard PC, router and analog phone inputs, packetize all the traffic, prioritize mission-critical or delay-sensitive traffic such as voice, and then to place each type of traffic in its own virtual circuit (VC) for DSL transport to the DSL access multiplexer (DSLAM). The DSLAM then feeds data traffic to private or public data networks while feeding the voice traffic to the VoDSL gateway. The gateway converts the traffic from multiple DSLAMs to a time-division multiplexed (TDM) format acceptable to a local, Class 5 circuit-voice switch, which passes on the traffic to the PSTN. The systems also enable the customer equipment to signal the Class 5 switch for provisioning of custom local area signaling service (CLASS) features including dialing plan and call forwarding.
Jetstream, CopperCom and other VoDSL vendors promise to make their equipment generally available this year. Due in the third quarter, for example, the CopperCom Gateway starts with support for 1,056 simultaneous calls and will be priced between $45,000 and $110,000.
Speed to Market
Adding flesh to the VoDSL movement, Denver-based DSL CLEC Rhythms NetConnections Inc. and MCI WorldCom Inc. reported successfully demonstrating toll-quality voice and high-speed data communication over a DSL-enabled copper phone line in New York.
The test employed Jetstream's CPX-1000 gateway and integrated access device (IAD) and the Cisco 6100 DSLAM. Voice calls were transported via Cisco's 8650 BPX IP+ATM switches through Jetstream's voice gateway interface to MCI WorldCom's Class 5 PSTN switch, then over MCI WorldCom's asynchronous transfer mode (ATM) network. Data traffic was transported to the Internet and also could be directed to a corporate local area network (LAN).
Together, Rhythms and MCI WorldCom say they'll develop DSL-based networking solutions that converge voice, data and Internet access and applications. "This type of solution can address the needs of corporations with remote workers and branch offices that must have high performance, the flexibility of both voice and data capabilities, and cost-effective management to justify outsourcing remote network management," Jim Greenberg, chief network officer at Rhythms, said in a prepared statement.
Additionally, Santa Clara, Calif.-based DSL carrier Covad Communications Co. announced successful testing of VoDSL using gateways from CopperCom and Jetstream, along with CO DSLAMs from Petaluma, Calif.-based Nokia High Speed Access Products, formerly Diamond Lane Communications.
"Such an integrated voice/data solution over SDSL could become a very cost-effective method of delivering toll-quality voice services to new customers that ICG might not otherwise serve," says Jon Lowry, senior director of ISP markets at Denver-based carrier ICG Communications Inc. ICG enjoys a partnership with national DSL provider NorthPoint Communications Inc., San Francisco, and is testing Copper Mountain DSL equipment with TollBridge gateways in its lab.
Carrier Class
The competition to deliver VoDSL and integrated DSL access systems already is heated. Announcements at SUPERCOMM included:
* CopperCom partnerships with DSLAM makers Alcatel USA; Cisco Systems Inc., San Jose, Calif.; Copper Mountain; Nokia; and PairGain Technologies Inc., Tustin, Calif., as well as CopperCom partnerships with DSL customer equipment makers Efficient Networks Inc., Dallas; FlowPoint Corp., Los Gatos, Calif.; Netopia Inc., Alameda, Calif.; Ramp Networks Inc., Santa Clara, Calif.; and Telocity Inc., San Jose, Calif.
* Jetstream partnerships with DSLAM makers AccessLan Communications Inc., San Jose, Calif.; Alcatel USA; Cisco Systems; Copper Mountain; Nortel Networks, Richardson, Texas; Promatory Communications Inc., Fremont, Calif.
* TollBridge partnerships with Copper Mountain, Netopia, Nokia and Paradyne Corp., Largo, Fla.
* Nortel Networks, noting its equity investment in Jetstream, introduced its own ATM-based voice compression technology, called ATM adaptation layer 2 (AAL2), now integrated into Nortel's Universal Edge 9000 DSLAM and its Passport 4740 IAD.
* Lucent Technologies Inc., Murray Hill, N.J., partnered with Copper Mountain to deliver PBX extension systems (already under testing by Rhythms NetConnections) while also introducing AAL2 technology in its AC 20 and AC 230 multiservice access devices.
Both DLSAM and gateway vendors promise to support tens of thousands of VoDSL and Internet protocol (IP) sessions per serving area. For example, AccessLan's newest PacketLoop swappable line cards can accommodate up to 19,200 digital VCs, assuming a 4-to-1 compression of each digital voice session. AccessLan also has partnered with Salix Technologies Inc., Gaithersburg, Md., to assure that VoDSL can be fed to emerging "class-independent," as well as circuit-switched telephony networks.
DSL carriers including Rhythms also have begun to employ DSL cross-connect devices from Mountain View, Calif.-based Turnstone Systems Inc. that, like circuit telephony cross-connects, provide loop testing and back-up switching for DSL lines that go down. Most systems also leverage well-established telephony protocols, including GR-303, an interface developed to allow rural digital loop carrier (DLC) voice systems to bring voice traffic into standard local circuit switches. Further, the DSL vendors say their equipment complies with North American carrier standards for compact design, redundant power supply and the ability to swap parts without bringing whole systems down, either at the CO or customer site.
"The DSL customer equipment is no longer just a modem or router, but a reliability device," says Peter Bourne, director of product marketing for Efficient. "You cannot kick a vice president off his phone to reboot that device."
Dynamic VCs
With so many vendors, the nuts and bolts beneath the gateways, DSLAMs and customer equipment will vary, as will each vendor's claims to superior capabilities and performance.
In other words, the religious wars between ATM advocates and frame/IP advocates is carrying into the emerging DSL realm. Covad already uses SDSL systems that employ ATM transport between the customer and the DSLAM, as do ADSL systems being rolled out by Atlanta-based BellSouth Corp., San Antonio-based SBC Communications Inc. and other incumbent carriers. In contrast, NorthPoint's Copper Mountain systems use frame-based DSL, and Rhythms NetConnections employs a mix of frame and ATM transport.
Many VoDSL equipment providers argue that ATM-based DSL is best suited to handle delay-sensitive voice and integrated access in general. The pitch: Through quality of service (QoS) and compression, ATM can improve on channelized 1.5mbps, T1 access lines over copper links. While T1 can accommodate up to 24 uncompressed analog voice transmissions, each over a fixed 64kbps, or DS-0, circuit, digital compression can multiply DS-0s at a 4-to-1 or even 8-to-1 ratio. AAL-2, a recently ratified ATM Forum standard, can compress 201 DS-0 circuits into a T1. It also can manage the integration of compressed voice and uncompressed fax or data traffic into a single VC. Additionally, ATM provisions bandwidth on demand for each phone call, then re-allocates the bandwidth to data and other uses when the call is completed.
"This combines voice and data in a dynamic way because it's ATM," says CopperCom's Stagnaro. "Customers all told us if the application is voice, it has to be ATM."
Similarly, although Lucent expects new differentiated services (DiffServ) and multiprotocol label switching (MPLS) protocols to inject ATM-like QoS and traffic-management capabilities into IP networking beginning next year, the company believes ATM is the mature, standardized technology for today.
"Only ATM handles compression signaling and can put multiple calls in the same cells, and only AAL-2 can put voice on the local loop so efficiently," says Dave Haas, director of customer located equipment (CLE) for Lucent. "ATM lost in the enterprise local area network to Ethernet, but AAL-2 shows so dramatically what ATM can do that it is finally going to justify ATM in the local loop."
In most ATM-based DSL systems, the DSLAM concentrates voice traffic and separates it from data traffic. An ATM switch passes the concentrated packetized voice traffic on to a PSTN gateway, which converts it to a TDM format acceptable to a standard PSTN circuit switch, using the GR-303 interface. Alternatively, the ATM switch can pass the packetized voice traffic into an ATM or IP backbone network for long distance transport.
Combining the DSLAM and ATM switch into one box, Promatory's Intelligent Multiservice Access System (IMAS) DSLAM combines DSL multiplexing with ATM QoS controls, ATM routing, ATM signaling and ATM local switching. This combination, says Promatory Marketing Vice President Timothy Waters, enables IMAS to allocate up to 128 VCs per port and to apply traffic management and QoS policing on a per-VC/per-application basis.
Efficient Networks, which teamed its SpeedStream IAD with Jetstream's CPX-1000 gateway and Nortel's Universal Edge 9000 DSLAM to demonstrate VoDSL at SUPERCOMM, also adopted ATM transport from its inception. "You can't force the customer to tear out a router or PBX, so you need a next-generation IAD with ATM-based, per-VC quality of service," says Efficient's Bourne.
Still, ATM has little experience in the local loop, and voice over ATM has been applied almost only between PSTN trunk switches at very high connection speeds. To help solidify ATM's place in access, CopperCom and other vendors have submitted to the ATM Forum an architecture specification described as "Broadband Loop Emulation Services."
Other vendors, including Copper Mountain, TollBridge and AccessLan, argue that combining frame relay VCs, IP DiffServ class of service (CoS) queuing, and MPLS end-to-end path management can achieve service integration and QoS more efficiently than ATM, which requires converting data packets into ATM cells then back again.
"We already use frame relay to establish up to 32 VCs per loop and to assign class of service priority, and we can employ IP compression to squeeze 16 lines of voice into a loop without AAL2," says AccessLan Marketing Director Kris Sowalla. "ATM traffic intelligence may be useful in the complex, multipoint, core matrix of switches, but it's overkill in a point-to-point connection like a local loop." Copper Mountain's Long agrees.
Arguing that more frame relay-based CPE exists than ATM CPE in the symmetric DSL realm, Long says that frame relay VCs in the local loop are sufficient to cordon off voice traffic and give it priority treatment. Further, he notes, advanced IP applications such as IP multicast--which deliver a single IP session to tens of thousands of end-user IP addresses--will not work over ATM without the arduous provisioning task of replicating ATM VCs to each user.
Whatever the mix of methods, the hardware and the partnerships that link end-to-end systems are forming fast. "We'll all be testing VoDSL thoroughly through 1999," Long says, "and then next year will be a blow-out."
