VoIP in the cloud tackles quality of service

Can service providers resolve all the complexities in delivering voice with reliable QoS to multiple enterprise networks in a cloud computing model? A trio of analysts weigh in with their forecasts for cloud VoIP.Cloud computing is a pleasing concept that conjures visions of headache-free IT services delivered by a provider who does all the worrying for you and owns all the machinery. Google Inc. and Amazon.com Inc. are already demonstrating that the cloud model can work for simple applications such as calendaring and storage. Soothsayers say this approach will evolve for more complex services such as voice communications.But quality of service (QoS) issues are fiendishly difficult to resolve in VoIP implementations on even one enterprise network. And unlike isolated and siloed services such as such storage, VoIP and next-generation unified communications (UC) have hooks throughout an enterprise network. Forrester looks into the cloudsAll manner of service delivery models are being lumped as cloud computing: software as a service (SaaS), managed services, outsourcing and hosted PBX. “It’s fair to view cloud computing as a continuum, but there’s danger in metaphors,” says Henry Dewing, analyst at Forrester Research. There are actually two types of cloud communications models emerging at the consumer and enterprise end. “Google has applications running off its servers and you can download a client that allows you to connect on the Web – but you can’t buy a T1 line from them,” he says. “AT&T, by contrast, actually owns the network resources that deliver the solution to you, so they can manage the bandwidth and plumbing as well as the fixtures.”Dewing is relatively bullish about the emergence of cloud computing for VoIP on the enterprise front. “It’s a matter of time before it evolves into a viable alternative to capital investments in VoIP infrastructure.”While QoS is a major challenge, Dewing doesn’t believe it’s insurmountable. “There are many ways to mitigate this,” he says. “You can deliver voice over a SIP trunk which has QoS associated with it so when traffic exceeds capacity, it simply turns off. But transport to the enterprise network must have some QoS on it too.”Another relatively new approach being developed by Microsoft Corp uses real-time audio codecs to manage QoS from endpoints, he says. “This puts error-correcting mechanisms like lowering the bit rate to insulate voice quality from the underlying transport, but this can’t be done infinitely. You must have enough bandwidth to carry voice or it won’t work.”The core QoS issue is that VoIP shares the network infrastructure with other non-VoIP tracks, so delivery of voice packets in real-time has to be done in a probabilistic fashion to avoid lags, jitter, dropped packets and other problems that can cause voice conversations to break down. “One of the ways service providers can handle this is by prioritizing traffic by class of service: video might be first, voice second, and so on,” he says. “But the entire network must share the same schema around QoS – since this is handled in a probabilistic fashion, it must understand when and how a packet will be there.”The difficulties today revolve around the different QoS standards adopted by major vendors such as Cisco Systems and Nortel Networks, and inconsistent standards as traffic hops from one network to another, he says. “The points where networks meet have problems, as they must pass information about the QoS associated with a particular packet. So if the cloud supports 12 classes but the enterprise only handles three, a translation has to happen, and it could be different every time traffic crosses over.” To circumvent this issue, network operators such as AT&T and British Telecom (BT) offer managed network services right up to endpoints as well as cloud communications services to guarantee QoS end-to-end, he says. “So they would manage your LAN as well, potentially setting up the equivalent of a VPN over a SIP trunk.”But Dewing says enterprises don’t appear to trust network operators to deliver UC services, and it’s reasonable to assume they’d have similar views about VoIP cloud services. According to a recent Forrester survey that asked enterprises which category of provider they look to for purchasing UC, network operators came last, after data network equipment providers, traditional voice system providers and software vendors.Even if all the technical QoS issues are solved, there are still intractable business culture issues around loss of control that may inhibit the success of cloud VoIP, he says. Uptake of centrex-type services, which are the equivalent to cloud VoIP services in traditional telephony and have been available for years, has never been above 10%. “It becomes a question of job security for the CIO sitting around with no reports or infrastructure. What history tells us is that the success rate of many outsourced types of services is low.”Last mile problem, writ largeCloud computing may be a sexy new buzzword, but providers aren’t offering anything new, says Carmi Levy, SVP of Toronto-based AR Communications. “It’s just a new way of describing services that enterprises are still having difficulty understanding. Providers are often just offering hosted PBX but hope their particular message will be seen as unique.”Levy says the term can be misleading when applied to enterprise services, as many assume these will be as headache-free as Google cloud applications offered at the consumer end. “There’s a danger in the perception that cloud computing is a cure for all that ails VoIP and that it means you no longer have to maintain your network infrastructure to support QoS, when in reality it’s just another means of delivering services.”Levy says he’s somewhat bearish about service providers’ ability to solve enterprise QoS problems in a cloud model. “And the reason is this perception that when you move to a cloud, you can hand over full accountability for VoIP to someone else.”At the consumer end, the last mile issue has dogged many VoIP installations, he says. “You still need sufficient bandwidth and other capabilities to support home VoIP, and you need cables going from the street to your home office.”By analogy, the enterprise equivalent to the last mile would be the LAN or WAN. “Once it gets in, it still has to travel through the enterprise network, so you still need some expertise, be it internal or hosted or managed or something. VoIP is an end-to-end service with significant last mile needs.”At present, many vendors purporting to offer VoIP as a cloud service are simply connecting an enterprise’s existing network to their cloud, he says. “I have a problem with the concept of VoIP existing completely in a cloud. You have to have infrastructure right up to the demarcation point on the premises to ensure QoS.” Larger enterprises are more likely to have existing infrastructure to contend with, but he concedes cloud VoIP may be a reasonable option for SMBs without an IT department or infrastructure looking to vendors offering end-to-end services. “SMBs are increasingly turning to hosted VoIP to avoid massive capital investments.” But enterprises that opt for cloud VoIP are ultimately exchanging one set of headaches for another, as their challenges become maintaining contracts instead of technology, he says. “The onus is on the buyer to ensure the vendor can provide bullet-proof VoIP with sufficient QoS. Then the shift is from managing infrastructure to managing the relationship with the vendor to ensure service level contracts are met.”Huge dental billsNotwithstanding the fact that VoIP has been around for over a decade, a recent survey noted that 16 per cent of users complained about voice quality, says Gary Audin, president of Arlington, V.A.-based Delphi Inc., a system integration consultancy.“That translates into one out of six calls, which is awful. Most implementers are still learning how to fix QoS problems, even though solutions are published everywhere. If these are the teething pains of a maturing technology, then the dental bills are huge.”Audin says he’s very bearish about the emergence of cloud VoIP for enterprises, as QoS issues are fiendishly difficult to resolve. Like squeezing a balloon, attempts to fix one problem often create another. To avoid jitter, for example, VoIP networks can be set to wait for late packets to arrive in the buffer – but then this creates delays that can also kill the conversation. He points out vendors such as AT&T setting up shop will have the same QoS problems, staffing issues, and capital investment decisions the rest of the IT industry faces, only larger. And offering cloud VoIP introduces a new set QoS issues into the equation, as security and privacy issues need to be factored in. “For enterprises doing VoIP over a public network, security is paramount,” says Audin. “But this ends up causing new problems as voice quality is connected to security. Encryption adds latency, and QoS markers often can’t be read in VPN tunnels.”If vendors bundle VoIP, lines and SIP trunking into their offering, then that might be a reasonable sell, he says. “But you still need stuff on the premises, depending on what vendors offer in the cloud. Phone calls are the trivial part – it’s in the business services and features that security and privacy become important.” And there are larger issues beyond QoS that will hinder the emergence of cloud VoIP that is truly ubiquitous for a very long time, he says. There are financial hindrances. “Carriers that put in cellular infrastructure in their regions, are they going to rip all that out for VoIP, or extend their capital investments?”On the flip side, there are many regions that don’t have cellular service or broadband access, he says. “If carriers can’t afford to put in cellular, how can they afford to put in VoIP? When most people talk about cloud VoIP, it’s really about one heavily-populated urban area talking to another. But there’s a lot of empty space around Edmonton and Calgary.”

VoIP in the cloud tackles quality of service

News | 06/19/2008 10:08 pm EDT

To keep reading, get a free trial.

Already a Subscriber?

Reuse & Permissions

Inside The Wire Report

Information

Hill Times Publishing

Get in Touch With Us