For the past years, I have been hearing more and more traditional voice technology, including the standard PBX, is going the way of the telegraph key: valuable and functional communications systems being replaced by new, bigger, better, cheaper technologies. Voice and data networks, once separate and distinct, are merging into a single network.
The PBX is dead or dying, to be replaced by networked telephony servers. Computers are doubling as telephones. Management of this new technology environment is easier and more efficient, and these efficiencies translate into savings… PBX Armageddon is on its way?
“Cisco Telecommunications” (since when?) vendor are gearing their sales pitches in order to win the “IT-influenced decision” to replace traditional PBX with their Cisco boxes (Call Manager). These soft PBXs run on NT servers; some PBX nodes are connected over ATM backbones. And our old friend, the Internet protocol (IP), is being combined with telecommunications technology to form a dynamic new hybrid: IP telephony alias Voice over IP (VoIP). And best of all, thanks to IP telephony, overseas phone calls are free! Wow! I believed our Board of Directors heard about this.
IP Telephony
For purposes of this mail, I will refer to the above technologies
Generically as IP telephony, meaning voice systems that are computer-based and use the Internet protocol to ride on data networks. Traditional voice communication has long been digitally based, including phones, switching, signaling, and so forth; what I am discussing here is the newest applications of computer and network-based technologies for voice communications.
Again, IT professionals are confronted with a familiar problem: how to separate the reality from the hype, is the revolution for real or simply a figment of an overactive media hype machine? Is the PBX really dead? More specifically, given that this new technology will indeed play a part in the next generation of telecommunications equipment and services, which components and systems should IT leaders buy now, which should be implemented later, and which will never pan out? What will be the impact of IP telephony on IT budgets? How will operations management, IT staffing, and the IT department organizational structure be affected? And don’t forget the end users…
What is Data and Voice Convergence?
IP telephony is a basic component of what is typically referred to by the industry as convergence. Convergence is the melding of voice, data, video, and multimedia technologies–formerly disparate entities–into a single, unified, digitally based technology. This new technology encompasses:
a) Transport and infrastructure–one network that now carries all electronic traffic over the same physical cable backbone, both on offices and to and from the outside world for VOIP alias IP Telephony.
b) Telephony servers–computers (ie. Cisco Call Manager- NT-based) that reside on the office network and convert (“packetize”) traditional calls to network protocols and then route them over data networks.
c) User interface and computer telephony integration–a single device, that is, the PC, handles all transmissions seamlessly and in an integrated fashion (voice calls, database access, video conferencing, Web access, e-mail, faxes, and so forth).
The obvious advantage of convergence is that instead of many things to buy, to install, to manage, to learn to use, and to pay for–cabling, connections, devices, tools–there is just one of each of these. Fewer moving parts mean (theoretically) smoother operations, happier customers, easier management, and lower costs. And since the voice call is utilizing unused bandwidth on the data network, voice essentially “rides for free” on the existing network infrastructure.
Wow ! so many of these advantages, traditional PBX sure die, IPT (soft PBX) sure win, sure can sell and sure got market demand but wait !!! There are many reasons I see for this unwillingness to jump completely on the “PBX is dead” bandwagon:
1) There is currently a very large, relatively satisfied PBX customer base holding substantial investments in equipment, infrastructure, and management. Managers who are happy with a sound, reliable technology investment are unlikely to jump at the chance to adopt the latest and greatest.
2) There are some serious technical problems as well. Latency and reliability is the most often cited problems, and other major hurdles also must be overcome.
Latency: –
The latency problem will sound familiar to data network managers. Briefly stated, it takes time to digitize a telephone signal, compress it, packetize it for data network transmission, transmit it through any number of on-and-off offices switches, routers, and buffer it at the far end to make sure all the packets arrive before transmitting it to the end user. At the far end, it takes more time to un-packetize, decompress, and turn it back into a phone signal. This process (minus the digitization and compression/decompression) is typical of all network transmissions. For typical data transmissions, latency isn’t a major problem. But for phone calls, latency causes the annoying delay between when a word is spoken and when it is heard, much as it was in the early days of long distance calling. Callers end up talking over the top of each other in a manner that is disruptive and not tolerated in our current business environment.
Table 1 illustrates the latency problem. The threshold of delay that is not noticeable to the human ear is considered to be 100 milliseconds, and a traditional toll call meets this standard. Even assuming that all of the above latency factors are and will be dramatically reduced, VoIP quality is not likely to reach toll quality any time soon, especially if the notoriously fickle Internet is part of the equation.
Table 1
Reliability: –
Perhaps more significant than latency is the reliability problem. Everyone’s experience of the telephone is that, when you pick up the receiver, you get dial tone almost 100 percent of the time. In fact, the actual percentage of telephone service availability is 99.999 percent, the famous “five nines” of reliability. That averages out to five minutes of downtime per year; any more than that is considered unacceptable.
Data networks, on the other hand, are nowhere near as reliable. Due to complexity caused by multiple protocols, vendors, service providers, operating systems, network management systems, and so forth, it is virtually impossible for data networks to reach the reliability bar set by the telecommunications industry. Table 2 indicates the average availability of various networks.
Table 2
Other Technical Difficulties:
Though latency and reliability are the most significant challenges, there are many other technical difficulties confronting IP telephony adopters. These include:
Full redundancy: –
Data networks are seldom designed with the degree of fail-safe redundancy familiar to telecommunications managers. I remembered not long ago a Cisco Engineer came out with a plan/BOM for a so-called fully redundant Cisco IPT network for Teledata (the whole of 6th floor) that cost almost S$500,000. Mr. Yang, you almost fell off from your chair. Even if we buy the ideal, what about power redundancy for the followings
1) MIS’s servers, routers, switches and so forth,
2) Datacom’s LAN center that host Call Manager
3) Avaya System that links to Call Manager via E1
I know Ciscoman will come to the rescue with UPS. But look, that means every single element (including servers, switches, routers and etc.) within the voice network path need to have a UPS for power redundancy. So much for full redundancy. It can be achieved, but at a high price.
Multiple routes, unpredictable contention: –
You never know exactly how a data transmission will travel to its destination; in fact, it will likely take multiple routes, making it difficult to manage and maintain a consistent, high level of quality. Unlike the circuit-switched telephone network, data networks are highly vulnerable to slow-downs during peak usage times, as any Web surfer customer can attest. I know Cisco will come and say “we have QoS build in our routers and switches for this problem but” [you knew there was a “but” coming, didn’t you?]. Again, that means every single element within the voice network path needs to have QoS in place that translate to changing almost every single network device that is not QoS friendly. Yes, it can be achieved, but at what price? Hello where are the customers?
Standards: –
Because it is still in its infancy, there are few standards governing how all the new technology works together. Even systems based on open architecture need to be able to communicate across vendor platforms; calls placed from IPv4 devices need to be able to reach plain old telephones and vice versa; data security standards (for example, encryption) need to be adopted as do QoS standards; and so forth. These standards are being established but are not there yet. Did I mention anything on IPv6 yet?
Signaling: –
IP telephony mirrors the old-fashioned sequential call setup that was used before the development of Signaling System 7 (SS7). Call setup can take more than three seconds to connect a call (SS7 takes less than one second), and it does not provide look-ahead routing and other standard SS7 features.
Voice-data convergence:
It hasn’t happened, because the convergence technology doesn’t quite work yet. And by doesn’t work, I’m referring to total cost of ownership issues. Ease of use, reliability and robustness–not to mention vendor interoperability–are they close to real? I’ll let you know when I get my hands on Cisco IPT. These issues dramatically impact the productivity of both the end user and those installing and maintaining it.
Perhaps the most telling question about the reliability of IP telephony can be stated with chilling simplicity: When were the last time you had to reboot your telephone? I never did, I don’t have to.
Time to make the move to IP Telephony?
PBX resembles mainframe long ago, IP Telephone and Cisco resembles
Personal Computer and Microsoft respectively. They arrived big time in the mid-80s and have changed the computing paradigm from mainframe/dumb terminal to networked client/server. Well, it happened before it will happen again. The question is when?
References
http://www.cs-ipv6.lancs.ac.uk/ipv6/documents/papers/stallings/
http://www.informationweek.com/677/77iuvoi.htm
http://www.networkcomputing.com/1024/1024ws1.html
http://www.networkcomputing.com/1021/1021fn.html
http://www.compassconsulting.com/articles/IPTelephony.html
http://www.internetweek.com/trends/trends081098-2.htm
http://www.internetweek.com/columns01/let060401.htm
http://www.net.fiu.edu/iptelephony/avvid_project_overview.html
http://www.cisco.com/warp/public/cc/pd/nemnsw/callmn/prodlit/callm_o.htm
http://www.cisco.com/warp/public/cc/pd/nemnsw/callmn/prodlit/callm_d.htm
