IP Telephony Comparative Analysis

Cisco IP Telephony v.s. Avaya IP Telephony v.s. Open Source IP Telephony

What I will during the next series of postings is to:

1. Describe the overall architecture of the Cisco IP Telephony solution.
2. Describe the overall architecture of the Avaya IP Telephony solution.
3. Describe the specific technical solution details for an exemplary 1500 phone extension/user deployment, both utilizing Cisco’s and Avaya’s solutions
4. Determine their approximate price list cost
5. Finally, compare both of them to a solution based on Open Source IP Telephony (Asterisk).
   

So on this one, I will cover Cisco’s IP Telephony.

STEP 1 – Cisco IP Telephony

Cisco is a recognized leader in IP communications and has recently developed the “Unified Communications” concept. As per Cisco’s website: “Using a systems approach, Cisco combines the strengths of intelligent networking with security, open application programming interfaces (APIs), and self-service business applications”.

According to Cisco:

“IP Telephony encompasses the full suite of telephony services enabled by VoIP, including the interconnection of phones for actual communications; related services such as billing and dialing plans; and basic features such as conferencing, transfer, forward, hold, and many more. These services might previously have been provided by a private branch exchange (PBX)”.

“IP communications evolves the IP Telephony concept to include business applications that enhance communications to enable applications such as unified messaging, integrated contact centers, and rich-media conferencing that combines voice, data, and video”.

Cisco’s Unified Communications concept “takes IP communications a step further with technologies such as Session Initiation Protocol (SIP) and presence and mobility solutions. These technologies unify and simply all forms of communication-independent of location, time, or device, where users can be reached at any time based on their preferences and can communicate through any media using any device”.

Here I will explore in further detail, Cisco’s IP Telephony solution architecture.

Cisco’s IP Telephony solution is very flexible, in order to easily accommodate for a wide range of requirements, especially size.

The main components of this solution are:

• Cisco Unified CallManager-Call-processing software that manages voice and video calls between IP phones, media processing devices, VoIP gateways to the public switched telephone network (PSTN), and multimedia applications

• Cisco Unified CallManager Express-Software embedded in Cisco integrated services routers to provide call processing for small businesses and branch offices.

• Cisco IP Communicator-Software that delivers advanced telephony functions to Microsoft Windows-based personal computers for Cisco Unified CallManager and Cisco Unified CallManager Express users

• Cisco Unified IP phones-Includes hard, soft, and video phones for all types of businesses and users from the executive office to the factory floor
  

Therefore, a number of different deployment configurations can be developed in order to best fit any given site requirements. It should be noted that the only limitation is the Call Manager capacity.

Usually the most efficient configuration is the one which considers a centralized data centre model. However, intermediary smaller and more dispersed topologies can also be implemented as follows:

• Large Site General Office ~ 500 users or more
• Medium Site Manufacturing Plant ~ 40 to 500 users
• Small Site Sales Office ~ less than 40 users
  

LARGE SITE (General Office) – A large site by definition is a site with greater than 500 users. At a high level the site would have its own Call Manager cluster to provide voice services to the site. All hardware for services, e.g. voicemail, voice gateway, conferencing and other application hardware would also be located at the site. The cluster can also serve as a centralized call manager for smaller sites.

MEDIUM SITE (Manufacturing Plant) –Here a small cluster would suffice for the Medium Sites (Manufacturing Plants) which would be hosted in the Large Site (General Office) Call Manager. Medium Sites would connect to centralized Call Manager through the Data Network (ideally a Private Data Network). At the sites there will be individual telephone handsets and the Voice Gateway or Voice Router(with SRST) providing connectivity to Private VoIP/Data Network and the Public Telephone Network.

SMALL SITE (Sales Office) – These is a configuration conceived for those small Sales Offices that usually do not have unlimited WAN bandwidth. Cisco Unified CallManager Express-Software is a feature that can be used for small sites (less than 40 users). Cisco Unified CallManager Express (ITS) software would reside on the Site Router and provides basic telephony and telephony features. With ITS calls would be made out via PSTN link. The Voice Switch (IP PBX) software will actually be hosted within the Site Router (not a Call Manager).


Based on the above shared site configuration examples, Cisco claims that: “Unlike telephony solutions from other vendors, Cisco Unified Communications securely integrates all information types-including voice, data, and video-using intelligent technologies that are built into, rather than onto, the network”.

I will leave here on the description of Cisco’s overall IP Telephony solution. In case you may want to get further details please feel free to contact us, request further details by sending to comment to this posting. Next time I will cover Avaya’s IP Telephony solution.

IP Security Overview

The false sense of protection of a firewall and an antivirus seems to be a trend in today’s IT world. Of course such devices offer certain protection against malicious attacks, but should not be the only solution to provide network and information security.

All size corporations and even government have been victims of data security breaches. Millions of credit card numbers, social security numbers and personal information data being stolen or sold are part of the daily news. Unfortunately, we are just aware of the “big hits”. It’s hard for all corporations to make public data breaches, since the impact to their business can be huge. Are you willing to trust your personal information or assets to a company which allows an employee to store in a laptop thousands or millions of records? Probably not, but you won’t know until you read it in the news.

How scary the scenario could be? Well, think that in September 2006 the US Department of Commerce reported that 1,100 of their laptops were “lost, stolen or missing” in the last five years. From this number, 249 contained personally identifiable information. In the same month, GE reported that a company laptop containing names and social security numbers of 50,000 employees was stolen.
On the other hand, we need to be cautious and do not panic with such reports, because this doesn’t necessarily mean that such theft will necessarily end in a financial or id theft result. Security businesses will take advantage of such news, and try to sell as much as possible.

So, how to protect my information and what is the right level of protection?
I will cover those topics in the next posting.

Going back to business...

Asterisk.... Do you mean Asterix??

"The year is 50 BC. Gaul is entirely ocuppied by the Romans..."

No, that is not Asterix the Gaul, who I want to talk about, but instead of what I thik, is the engine fueling the upcoming and biggest Revolution on the Corporate and Business oriented Telephony industry.... Asterisk !!!

Asterisk, is the most popular Open Source IP PBX platform around. Based on the Linux Operating System, it offers the full features of a full fledged PBX at a small - very small - fraction of the cost.

For those not familiar with Asterisk let me refer back to some basic description, coming out of a very useful, very complete Wiki from www.voip-info.org:

"Asterisk is a complete PBX in software. It runs on Linux, BSD, Windows and OS X and provides all of the features you would expect from a PBX and more. Asterisk does voice over IP in four protocols, and can interoperate with almost all standards-based telephony equipment using relatively inexpensive hardware.

Asterisk provides Voicemail services with Directory, Call Conferencing, Interactive Voice Response, Call Queuing. It has support for three-way calling, caller ID services, ADSI, IAX, SIP, H.323 (as both client and gateway), MGCP (call manager only) and SCCP/Skinny. Check the Features section for a more complete list.

Asterisk needs no additional hardware for Voice-over-IP, although it does expect a non-standard driver that implements dummy hardware as a non-portable timing mechanism. A single (or multiple) VOIP provider(s) can be used for outgoing and/or incoming calls (outgoing and incoming calls can be handled through entirely different VOIP and/or telco providers)

For interconnection with digital and analog telephony equipment, Asterisk supports a number of hardware devices, most notably all of the hardware manufactured by Asterisk's sponsors, Digium. Digium has single and quad span T1 and E1 interfaces for interconnection to PRI lines and channel banks. In addition, single to quad port analog FXO and FXS cards are available and are popular for small installations. Other vendors' cards can be used for BRI (ISDN2) or quad- and octo- port BRI based upon CAPI compatible cards or HFC chipset cards."

For further details you can also check the "Official Website" at: http://www.asterisk.org/

The Next Big War: Asterisk vs Proprietary IP Telephony Solutions !!

As you may recall from my previous post "VoIP and IP Telephony", I think that the elevated costs of proprietary IP Telephony solutions, like those from Cisco, Avaya, Ericsson and others, are preventing the huge explosion expected from IP Telephony. This is, customers are not seeing a clear and compelling enough ratio between the hard cost savings and the huge investments required. Basically their feeling is that they are not getting a good enough "bang for the buck".

This is what I think Open Source IP Telephony in general and Asterisk in particular provide. Due to the combination of low cost and full features offered, Open Source IPT solutions like Asterisk will represent the "Tipping Point" that will move IP Telephony into the mainstream and effectively send traditional PBX solutions right into Garage Sales all over the industry.

What about Reliability??

Some people may argue (specially those trying to sell Cisco's and Avaya's solutions) that....this is Open Source !!!

This is, being a solution based on Open Source, Linux and thus a bunch of volunteer geeks doing this as a hobby, it will never provide the levels of Availability, Reliablity and such required by Corporate users.

This is like going back to the days when people claimed that Linux servers will never be adopted by companies like HP and IBM, or those days when people were saying that running live voice calls over an IP network would simply not provide the levels of quality, availability and reliablity (99.99999% and stuff like "people are used to get a dial tone no matter what) that the PSTN provided.

In both cases the defendants of legacy were WRONG!!

I firmly believe that this time around, once again, the defendants of legacy (in this case proprietary IPT solution) will be proven wrong again!

Open Source IPT and Asterisk are indeed still in their very early infancy, but over time, I predict, they will dominate the market, if they are not starting to quietly do so already... Time will Tell.

Hasta la Proxima!!

Asterisk

Sigamos con las Otras Hierbas ... "United We Stand, Divided We Fall"

One last time and I promise I'll get back to business....

Para este otro posting de las "Otras Hierbas" quisiera retomar uno de los comentarios que recibi en el posting anterior. Este comentario, dice asi:

"La democracia se construye día a día. No es facil ni debe estar todo mundo de acuerdo. Si hubiera acuerdo no sería necesaria la democracia."

Yo, coincido con ese punto de vista. La democracia es una jornada, donde el objetivo es reunir a aquellos que pensamos diferente, para compartir puntos de vista.

Pero creo tambien, que esa reunion de puntos de vista divergentes, deberia crear un proceso virtuoso en el cual se decubran las conincidencias y a partir de estas se llegue a acuerdos.

Ahora, tambien estoy conciente que los acuerdos nunca pueden ser totales, ni en todo, ni para todo.

Sin embargo, deben existir acuerdos fundamentales, acuerdos minimos, que nos permitan convivir de manera pacifica en medio de nuestras diferencias, pero donde el punto mas importante a mi manera de ver, es que al encotrar nuestras coincidencias, las tomemos y en base a ellas construyamos una comunidad, una sociedad, un pais mas fuerte, mas libre y prospero.

United We Stand / Divided We Fall

Hace no mucho tiempo, tuve la oportunidad de vivir y trabajar fuera de mi pais. Observe, compare, rechaze y aprendi mucho. Nunca, voluntariamente, cambiaria a Mexico, por ese o ningun otro lugar, por algo me regrese... pero una de las cosas mas importantes que aprendi se resume en un dicho comun que tienen alla y que dice asi:

"United We Stand"

y que como corolario, advierte:

"Divided We Fall"

Creo, que dice mucho y tiene mucho que podriamos aplicar a nuestra realidad actual.

El pais al que me refiero, es muy diverso. Tiene gente de muchas razas, de muchas religiones y con muchas diferencias. Sin embargo, a traves de su proceso historico han aprendido, que para poder ser un pais prospero, fuerte y en gran parte de su Historia, libre, deben permancer Unidos, dentro de sus inmensas diferencias.

En los momentos criticos de su Historia, han sabido mantenerse unidos y una vez unidos han sido capaces de vencer cualquier obstaculo, sea interno o externo.

Hay muchas cosas que se le pueden criticar a ese pais, pero algo que se les debe reconocer es su prosperidad. Claro que hay pobres y muy pobres, pero no al grado que sufrimos ahora en Mexico.

Mexico Unido Jamas Sera Vencido

Al revisar la Historia de Mexico, encontraremos que las crisis mas fuertes y dolorosas de nuestro pais, se han dado cuando hemos sido una Nacion Dividida. La Guerra con Estados Unidos, la Intervencion Francesa, la Invasion de 1914, y aun la Conquista, no son mas que ejemplos de las consecuencias de permanecer divididos y no ser capaces de encontrar nuestras coincidencias.

"United We Stand / Divided We Fall", se podria relacionar con nuestro muy usado dicho: "El Pueblo Unido Jamas Sera Vencido", pero creo que hace falta llevarlo un paso mas alla, y ese creo es el paso critico, el acuerdo critico que nos falta, para poder en cambio decir: "La Nacion Unida Jamas Sera Vencida" o "Mexico Unido Jamas Sera Vencido".

Esto no quiere decir, que renunciemos de nuestras creencias o renegemos de nuestras convicciones, pero si aplicamos de manera correcta la democracia, deberiamos de ser capaces de aceptar nuestras diferencias, respetarlas y por encima de ellas reconocer nuestras conincidencias y en base a ellas hacer de Mexico un pais mas prospero, libre y fuerte.

Pasemos a las "Otras Hierbas"....

For those two, or maybe three (if my dearest wife hasn't forgot already)that follow this Global Telecomm Consulting blog, I offer my apologies because I will take a "recess" from the main topics of discussion and in turn, get back to Spanish and talk about Mexican Politics!!!

Bueno, pues pasando a las otras hierbas...

Acabamos de presenciar lo que sinceramente creo es un momento historico que marca el proceso que se ha venido desarrollando desde hace varios años, tal vez decadas, en la relacion de poderes dentro de la sociedad Mexicana.

En resumen, un cambio profundo en la Historia de Mexico.

Sin que hubiera violencia fisica de por medio, el Congreso de la Union, por medio de una de sus bancadas, dio una muestra de fuerza e independencia real frente al Poder que desde hace Siglos, venia marcando el curso del Pais.

La tradicion historica de Mexico, marca que el poder de un solo hombre, desde el Tlatoani, pasando por el Virrey, Su Alteza Serenisima, hasta el Señor Presidente, regia el destino de la Nacion... No mas!

La Logica del Poder

En la logica del poder, existe el poder formal y el Poder Real.

El poder formal en Mexico(hasta el dia de hoy), es el que se comparte entre Ejecutivo, Legislativo y Judicial.

El Poder Real...ese no se comparte o no se compartia.

El Poder Real es el que impone su voluntad. El Poder Real es el que entra (o entraba) al Congreso, como en su casa...entre aplausos, vivas y hasta caravanas...
Historicamente, en Mexico, el Poder Real lo tenia el Presidente de la Republica.. No Mas!!

Cuando el Presidente no puede imponer su voluntad ya mas, es por el que lo ha perdido.

Democracia Real en Mexico?

Cuando el Presidente, no puede entrar al Congreso de la Union, es por que dentro de ese Congreso ha surgido otro Poder Real que se le enfrenta.

Al darse ese enfrentamiento entre poderes reales, se genera una autentica division de poderes. Se genera un verdadero balance de poder.

Esa division del poder real, es la condicion basica de una Democracia Real.

Este ha sido un proceso muy largo. Comenzo en 1968 o tal vez antes... pero el dia de hoy, creo, hemos asistido a su Consolidacion. Bienvenida!

Nunca antes, habia escuchado el Himno Nacional con tanto orgullo, como cuando se entono en el Congreso de la Union, despues de que Vicente Fox: "Entrego y se Fue"

The Case for Open Source

IP Telephony is still in its infancy. However the only thing constant in life is Change. Change just never stops... Thus what I think is going to be next breakthrough in voice communications is now starting to show it's face.... Open Source IP Telephony !!!

There is a big debate going on between the proponents of "proprietary" technology and those of Open Source, thus before I get into the details of Open Source IP Telephony, I would like to first explore the case for Open Source.

Some LINUX History....

In order to provide a brief and proper description, I will borrow a few paragraphs, from some material I recently got:

"In 1991, a Finnish university student named Linus Torvalds decided that, "for the heck of it," he would write his own Unix operating system. Today, Linux is a significant chunk of the IT market, making up 2.8 billion dollars of the server market.

Linux is an operating system, just as Microsoft Windows XP or Macintosh OS X. While the many versions of Windows are all produced by a single company, Microsoft, the many versions of Linux are actually offered by several companies and volunteer groups. Each of these versions is called a distribution, which is a fancy way of referring to a package containing Linux and lots of tools. "

The key word on the above is VOLUNTEERS....

There are many people who are (or used to be, like myself) mightily confused at this whole volunteer aspect of Linux. To try to grasp what's really going on, it's important to take a closer look at two key terms being: Open Source and free software.

In 1984, Richard Stallman started the free software movement. (Notice that the free software movement started before Linus Torvalds began working on the Linux kernel.) Stallman began two organizations around this time, the GNU Project, and then shortly after, the FSF (Free Software Foundation).

Free software, as defined by the FSF, is a "matter of liberty, not price." To qualify as free software by FSF standards, you must be able to:

• Run the program for any purpose you want to, rather than be restricted in what you can use it for
  
• View the program's source code
  
• Study the program's source code and modify it if you need to
  
• Share the program with others
  
• Improve the program and release those improvements so that others can use them
  

Again, notice the one thing missing here -- the FSF doesn't require that "free software" actually be given away for free!

You can charge for free software under their definition. You only have to give away your source code to the people who paid you for the software.

Basically Free Software is.... "Free, as in freedom."

Open Source

Open source generally refers to the ability to at least view the program's source code and preferably modify it and re-release those modifications as well.

So, what does all of this have to do with those volunteers working on the Linux? Some of the many reasons that programmers, artists, technical writers, and more participate in open source projects are:

• Experience: If you're trying to build a career or a good reputation on your technical field, it's great to be able to work on such a project and point to exactly what you did as an example of what you're capable of achieving. In fact, many open source and free software developers are hired to do work very similar to what they were doing in their volunteer projects -- on the strength of people liking what they saw and knowing that these programmers already know how to achieve the goals they need to reach.
  
• Pride: Developing software or IT solutions so good that people looking at it gasp at its elegance is a matter of pride. It's easy to hide sloppy work in proprietary solutions, where no one can see what you did. When people all over the world are combing through your work, there's no way to fake your way through it. You know what you're doing or you don't.
  
• Community: There are strong bonds formed within the open source and free software communities. Being part of groups in which people are genuinely trying to make a difference in the world has a definite positive factor.
  

There are companies that pay people to develop open source programs. Many people can't imagine how anyone could make money doing this, but there are a number of companies surviving and thriving on this business.

Most of their profits come from selling services based on the open source products (consulting, customization, training, integration, implementation, support, and more).

Many of the reasons that these companies chose the open source and free software direction are the same as those individuals that do it. However, another key reason is simply cost. Open Source products are usually much less expensive to develop, test, deploy and support than proprietary ones. This is an aspect that I will further develop on upcoming postings...

Eso es todo por hoy amigos!!!

Open Source

VoIP and IP Telephony

The Internet

The Internet is a network based on the IP protocol (more specifically TCP/IP). These network is built based on Routers and Switches interconnected by data links. It is important to point out that in today's market most of the Routers and Switches that power the Internet are those manufactured by Cisco Networks.

The main characteristic of IP Networks is that the information is transmitted as packets of information. Each packet having a piece that contains the address of the destination and the source(usually called the header) and another piece containing the information to be transmitted. Much like a letter and its envelop in the mail.

Initially the Internet was used to transfer files of different types of data between computers (mainly computers of the US goverment (Deparment of Defense) and Universities peforming reserach. Then it evolved to the transfer of other type of files (images, e-mail) used by businesses and the general public and later on web pages on the World Wide Web.

The Internet thus became an ubiquotuos network. Another key item is that there exist two "types" of Internet. The Public Internet, the one we all use at our homes and the Private Internet or Intranet, which is a number of different private networks where private entities such as Banks, Corporations, etc.. have built IP Networks that are closed to the public and intended for their own private use.

On the other hand, parallel to the Internet we have the Public Telephone Network (PSTN). The main difference between them is that the Public Telephone Network was built around Circuits and not Packets. This means that when a connection is established on the Public Telephone Network a single circuit is dedicated only to that connection or call. Usually a telephony circuit has 64 kbps available, but the voice call takes only around 8kbps typically, thus leaving a great amount of bandwidth idle or "wasted". Important to note that equipment manufacturers such as Lucent, Avaya, Nortel, Ericsson and Alcatel among others, dominate the traditional Telephone Network.

Once the Internet was mature enough, around the late Nineties and around the year 2000, some people started to see the benefit of combining both networks (the Internet and the PSTN) into a single network.

At that time, most entities (both private companies and public carriers) have to support two different networks. One for Data (the Internet or Intranet) and one for Voice. Each network required its own Maintenance, Support Staff and Development.

Voice over IP (VoIP)

One of the most simple definitions of Voice over IP (VoIP), is that which says that it is the Telephony solution where the Internet (or Intranet) is used to transport voice calls.

As introduced in the paragraph above, VoIP came up as an idea to consolidate both the Data Networks and Voice Networks into a single one, thus (ideally) cutting the cost of Maintenance, Support and Development by half.

Companies such as Cisco, developed technology on their Routers and Switches that would allow for voice calls to be carried on top of the IP protocol via the use of Gateways to "translate" the PSTN protocols (CAS, CCS, ISDN, SS7, etc..) into the IP protocol used by the Internet.

Initially, some people pointed out that the Internet would never be as reliable as the Public Telephone Network to carry voice calls. They based on this on the need that the IP Network had at the time to maintain backup links to provide a reliable service. They claimed that once the primary link went down, the voice call would go down as well before the Routers were able to "transfer" the call into the backup circuits. Thus, people used to the "all-to-reliable" Dail Tone would not tolerate this.

In response the proponents of VoIP, developed a number of techniques to ensure the routing of voice call over the IP protocol would be as reliable as in the Public Telephone Network. They also developed mechanisms to ensure that the quality of the voice during the call would be as good or better than the quality offered by the Public Telephone Network. The popular term for this techniques and mechanisms is "QoS" or "Quality of Service".

QoS, turned out to be an extremely succesful development.

At that time, pilot tests were conducted at most Major International Corporations and initial deployment of VoIP took place.

Initially VoIP was used as a "Toll By Pass" solution by private companies. This is, companies took their private traffic (usually calls between their offices across the country or the world) and routed it over their private Data Networks (Intranet) instead of sending those calls to the usual Long Distance carriers (AT&T, MCI, Sprint, and others). By doing so, this pioneer companies achieved multi-million dollar savings on Telecomm costs.

They did so, by connecting their Traditional Telephone equipments (PBX) to their Intranet Routers, having the calls transported over their Private Networks up to the destination point and then having the Routers at the destination points connected to the PBX systems at the offices or sites where the calls were to be terminated.

VoIP or.... IP Telephony ??

An extremely common mistake is to think that VoIP and IP Telephony are the same... They are NOT !!!

IP Telephony is the next stage of development of VoIP.

Once the VoIP Toll by Pass solutions were fully tested and their potential as cost savings mechanisms was fully demonstrated, people wanted to go one step beyond. This is to bring IP Voice communications up to the end users desks. Thus, the idea to replace the traditional PBX systems came into being.

Once again, Cisco Networks took the lead, by developing their AVVID solution. This solution basically replaced the circuit-based, hardware based proprietary telephone switch by a sever/blade-based, software-based IP telephone switch. The Cisco Telephone switch is commonly referred to as the Call Manager.

The Cisco Call Manager (or more appropriately Cisco's AVVID) solution is a powerful set of technologies that allows not only for IP Voice communications but also enables IP Videoconferencing, IP Audiconferencing and IP Messaging.

One of its main benefits/strengths is the ability to support a wide number of geographically dispersed offices or sites out from a single Call Manager cluster, thus dramatically reducing maintenance costs and allowing for centralized support and reduced support staffs.

At this point in the game, traditional telephone equipment manufacturers such as Avaya, Ericsson, Nortel and others started to see their telephone business models at risk in case they didn't jump into the IP Communications wagon.

By now they all have developed their own IP Communications solutions, adding a new component to the future voice technologies equation.

What Road to Take into VoIP?
Evolution or Revolution?

The proper answer to this questions (as everything in life) depends heavily on the specifics of each case.

But in a general sense it could be said that the overall lines of the figth for the future IP Telephony market were drawn between Cisco on one side and Avaya, Ericsson, Nortel and others in the following manner:

Cisco proposed a revolutionary change. This is for a given customer to take advantage of the benefits of the Cisco AVVID solution, the customer has to forklift most or all of their previous office telephony infrastructure (PBX, cabling and phone sets), thus basically take what in most cases is a perfectly working system, probably recently upgrade (due to Y2K) and in most cases not fully depreciated investment and put it out in a Garage Sale....

It does not take a Financial Advisor to realize that the economics of doing so are not exactly great.

Experience has shown in some cases, that even considering all the cost benefits of VoIP it hardly pays out to dispose of the previous technology when the system has not been fully depreciated yet.

On the other hand, and in order to tackle this strategy flaw, equipment manufacturers such as Avaya, Ericsson, Nortel and others are taking advantage of their market dominance in the Telephony Market to propose an Evolutionaty Approach. This is they offer their own brand of IP Telephony while at the same time keeping the ability to run the old telephone system, thus letting customer migrate at their own pace.

In my opinion, the disadvantages of this approach are mainly two:

1 - Since not everybody gets IP Telephony and usually not everybody gets them at once or in a short period of time, then the corresponding cost and productivity benefits are also slow to show up.

2 - Traditional Telephony manufacturers such as Avaya, Ericsson, Nortel, Alcatel, Siemens and others have developed their traditional telephony solutions in a mostly proprietary way. This is, each one of them has its own Operating System, Configuration process and Administration process which requires specific (and hard to find) skills that as a consequence are usually expensive. My personal experience is that such proprietary mindset is still present on their IP Telephony solutions, thus not making them open enough as an IP based standard based solution should probably be.

Regardless of Revolutionaty or Evolutionary the fact of the matter is that to this date IP Telephony as the next big thing in the Telephony Industry has failed to explode and dominate the market as initially expected.

In the next posting, I will cover what I see as the new kid on the block......... Open Source IP Telephony !!!

Hasta la Proxima!
VoIP IPTelephony