Skip to main content

Vetting VoIP

Cable’s route into voice-over-Internet protocol services is travelling across an awkward amalgam of century-old telephone issues, such as battery-backed power supplies. But there are also futuristic challenges, including “follow-me” integration with wireless/mobile services.

Along the way, the new corps of telephony experts at MSOs and the vendors seeking to sell them voice solutions are confronting multiple fundamentals of today’s phone reality.

Their challenges range from deciding how to use the emerging Session Initiation Protocol standard to implement VoIP versions of “E911” emergency access. The VoIP highway also includes detours into IP Multimedia Subsystems and requirements for compliance with the Communications Assistance for Law Enforcement Act (CALEA). An array of soft-switch technology, plus the increasingly competitive market for low-priced embedded Multimedia Terminal Adapters are also part of the VoIP migration.

Not to mention the Next Generation Network Architecture, the industry’s vision for future cable technology — now in its early evaluation stages at Cable Television Laboratories Inc. Digital voice services figure deeply into the NGNA agenda.


Nonetheless, VoIP’s complexity has its rewards — starting with the lower equipment price, which can be half the cost of time-division multiplexing (TDM) hardware, according to Jay Rolls, vice president of telephone and data engineering for Cox Communications Inc.

Cox, which has more than 1 million voice customers (most of them using legacy TDM-switched facilities), has set its highest priority for the year ahead to convert all of its switches to hybrid devices, able to handle both VoIP and TDM.

Cox’s primary goal for 2006 is “capping our TDM and converting over to VoIP,” Rolls says. “That’s as big a project as launching new markets for video on demand.”

Also smoothing the cruise toward VoIP is the relatively easy upgrades of headend equipment. Cable-modem termination systems can generally be prepared to handle voice services through the installation of software.

“CMTS went through an evolution,” says Mark Baikes, director of marketing at Cisco Systems Inc.’s broadband subscriber and applications unit. He cites the “ever-increasing capacity for data and voice” as a continuing driver for upgrades.


Baikes singles out the value of network address translation (NAT), an Internet standard that enables a local-area network to use one set of IP addresses for internal traffic and a second set of addresses for external traffic.

These translations can sometimes create problems in deploying VoIP, although he cites a Cisco solution that can be installed to resolve such hurdles.

Time Warner Cable has installed Cisco BTS 10200 soft switches at its seven regional data centers, most of which have multiple switches. Time Warner senior vice president of voice Gerry Campbell says the price advantage for VoIP technology is significant, and he expects that “when Comcast [Corp.] more aggressively enters this space, the prices will go down” even further.

Rolls says that at Cox headends, technicians made code changes to the DOCSIS 1.1 (Data Over Cable Service Interface Specification) on CMTS equipment. The process included upgrades to a dynamic quality of service. Easing Cox’s transition is a Nortel Networks “bolt-on” product, which transitions its DMS 500 switches (now used in all Cox’s TDM markets) to hybrid switches, able to handle VoIP.

Motorola Corp., which does not offer its own softswitch, has conducted integration tests with all the major switch vendors.

“You want to have infrastructure that is high-performance and also supports full redundancy, carrier-class implementation and hitless software upgrades,” says Jeff Walker, Motorola senior director of marketing. “You don’t have to take customers out of service [when you] load software into the system.”

Cedar Point Communications’ Safari C3 Multimedia Switching System exemplifies the emerging generation of integrated VoIP platforms.

“We’re integrated into a single device with an interface to the CMTS,” says David Spear, Cedar Point executive vice president of strategy and market development. He contends that MSOs can garner lower operating costs by integrating the call-management system, the media gateway, signaling gateway and CALEA servers in a technology bundle that interfaces with existing CTMS equipment.

Spear also stresses the value of DOCSIS 2.0, now being adopted by more MSOs. “It is very important for increasing the overall bandwidth as it applies to other quality of service [factors] for upstream capabilities,” Spear adds. Comcast, Charter Communications Inc., Insight Communications Co. and Bresnan Communications are among the MSOs using Safari C3, often at their smaller systems.

Rolls says that about half of Cox’s CMTSs have been upgraded to DOCSIS 2.0, about the same ratio as Cox’s cable modems.


The move toward SIP is high on the agenda for many vendors and operators, especially since the protocol is being developed for wired and wireless services. Although it is not currently part of the packet-cable technology, cable is evaluating SIP on several fronts.

“The significance of SIP …is that it can be married to an existing cable modem,” Jeff Walker of Motorola explains, emphasizing that “operators won’t have to replace existing cable modems.”

John Sweeney, Scientific-Atlanta Inc. director of product strategy and management for IP subscriber products, agrees. “SIP is starting to gain traction,” Sweeney says, pointing out that at a recent CableLabs meeting, there was movement to put SIP into future devices.


He adds that although SIP “may not be operating Synchronous Code Division Multiplexing, the systems “give more throughput to increase upstream capacity.”

Baikes of Cisco sees SIP as “an accelerator in the convergence of telephony … and entertainment.

“What’s also interesting is that SIP is being adopted in wireless,” Baikes adds. He also observes that, “Consumer-electronics companies are beginning to make convergence devices without knowing who is going to run them.”

Cedar Point’s Spear points out, “We’ve already built SIP as part of our platform. It just become another access device that we talk to.” He says a SIP device could sit behind the cable modem or be embedded within it.


“MSOs are seeing that they can achieve penetration that is so high they could become the dominant carriers,” is the enthusiastic evaluation of Stan Brovont, vice president of marketing and business development at Arris, which supplies VoIP and other hardware to cable operators.

He says that MSOs are “looking for iLEC [incumbent local-exchange carrier] feature parities,” starting with the major custom-calling features such as call waiting and forwarding. Brovont expects that “price competition is going to be a fact of life.”

Powering the eMTA equipment is a fundamental challenge, to assure that voice customers maintain the always-on voice service they received from telephone companies. Four-hour back-up batteries are today’s norm, but most systems are upgrading to at least eight-hour batteries.

For example, Bresnan has standardized an eight-hour back-up battery in the home equipment and at its nodes. At its headends, Bresnan has back-up generators.


“Digital phone” is becoming the preferred term for cable’s telephony service — and it seems to be catching on. Cox, Time Warner, Bresnan and most other large MSOs are selling their VoIP services as “digital phone” to accompany their digital cable channels.

A bigger differentiator is how the voice infrastructure is set up. According to Spear, “Each customer lays out its network in different ways … [depending] on how many contact points they want to the PSTN [Public Switched Telephone Network].”

He says that many gateways reach about 60,000 subscribers, but he notes that many of the softswitches “are getting pushed out into the network.”

“Regionalization gives groups more control over their offerings,” Spear contends.

Bresnan, which launched its first VoIP service in Grand Junction, Colo., in March, has signed up “several thousand customers” in the four markets where VoIP is now available (including Cheyenne, Wyo.; Billings, Mont.; and Durango, Colo.).

Bresnan expects to have 70% of its homes passed ready for telephony service by the end of this year, and nearly 95% of its customers ready for VoIP service by the end of 2006, according to Lenny Higgins, senior vice president of advanced services for the MSO.

“We’ll do some plant hardening, reducing the node sizes to make it tighter for telephone service,” Higgins says. Bresnan partnered with Net2Phone, which handles back office and termination services.

The systems have Cedar Point equipment as well as Cisco UDR hardware, Cisco’s primary CMTS equipment, in a redundant configuration. Most of its consumer premises equipment is made by Arris.


The coming year is likely to bring more features as well as increasing appetite for VoIP rollouts. Spear sees home-network integration and mobile virtual network operations as key drivers for voice service in 2006.

Farshid Mohammadi, general manager of switching at UTStarcom Inc., and marketing chairman of the International Packet Communications Consortium, also foresees VoIP expansion “either organically or through third-party wholesale models to reduce risk.”

In 2006, Mohammadi expects “the introduction of a wireless ... to complement the triple play.” He also embraces the follow-me concept, which he calls “Fixed Mobile Convergence,” characterizing it as a major attraction for “the enterprise segment — an untapped market for cable operators.”