IMS: Data's New Daddy

This rare guest column has been written in response to the July 1 Unstrung article IMS Taxes Mobile Voice, which reported that running VOIP over cellular networks could use up to four times the capacity of circuit-switched calls. That's not the whole story, argues inCode Wireless analyst, Arturo Fermin, especially as IMS is really all about the creation and deployment of new data services.

The question of efficiency in cellular networks has been, and will continue to be, a complex one. When inside the laboratory, it may be quite simple to pick one particular statistic or metric to compare different types of approaches to take one item of information from point A to point B. Comparing results will be quite straightforward. However, extrapolating to a wireless carrier will not.

A myriad of variables affect efficiencies. Bandwidth is one of the many that reside within the RF domain of the service provided by wireless carriers. If we take the somewhat sterile, clinical measurement of 12 kbit/s for a GSM circuit-switched voice call and contrast it with 45 kbit/s for an IP packet-switched call, it may indeed sound inefficient. One thing to be considered is that the codec used will greatly influence the needed bandwidth, and compression technology is advancing rapidly.

If we take a step back and include more networking gear in the picture, we would have to deal with another conundrum: circuit switched (CS) versus packet switched (PS). From the aforementioned comparison, it would follow that we are taxing the network using four times the bandwidth for a voice call. But consider that when a CS voice call is placed, a circuit is establish and used, whether you are talking without interruption or eagerly waiting for the other party to utter a word. The resources are engaged and there is nothing anybody else can do with them while you are transferring 12 kbit/s of nothingness.

Just imagine firing up your instant messaging program [ed. note: yes, just imagine!] and contacting four friends. After greeting them, you flip from one to the other while browsing the Web and downloading a presentation you must review. If each instance of your IM would engage resources à la CS, your download would be a long wait. When we use PS network paradigms, we are also able to put more information into the same pipe.

After all, you have only one ADSL “pipe” for all the IP-based software in your PC. A short time ago, you only had a microphone and a speaker in your cell phone. Sooner than later, you will want to use your cell phone for something else – not just talking. That is when, in my opinion, we can start comparing paradigms and thinking through the efficiency issues.

That said, if we get bogged down either on the bandwidth or the network taxonomy issues, we would be missing the key part of the story unfolding in today’s market: the customer experience.

To think that carriers are heavily investing in overhauling their networks for 3G services to provide more “traditional” voice calls would be, at the very least, a huge underestimation of their plans. Since voice ARPU [average revenue per user] has been declining for many years, this would be a financially untenable investment. European carriers in particular dream of the day when IP services will be as huge a success as SMS [text messaging]. It would not hurt if these IP services also shared the staying power of SMS. Carriers are investing heavily in 3G to regain lost ARPU from voice services, and they will succeed as long as they are able to design and provide new services.

Convergence is a good starting point as long as we do not lose our focus. We must always keep in mind that IP Multimedia Subsystem architecture is not the end, only the means. We in the telecom and IT industries have a tendency to get dazzled by “the new.” In this case, we need to embrace IMS as the means to create and deploy “the new.” As we become more proficient and experienced in convergence, we will be better prepared to imagine what’s ahead.

We need to start focusing on what’s to come – services we will implement in radically different ways – but base our expectations on the conviction that the lessons we learned in different industries, markets, and technologies will serve as the alphabet of new offerings. All the letters are there. We just have to spell them correctly in new phrases.

— Arturo Fermin, architect at inCode Wireless, has spent the last 15 years in information technology, networking, and telecom, working on emerging technologies projects in Europe and the Americas. For the past five years, his emphasis has been in implementing 2.5G and designing 3G systems using 3GPP, OMA, and OSA standards. Based in Spain, he is also actively consulting in new service creation areas, providing expertise and insights into the convergence of IT and telecom for next-generation networks. Please visit inCode Wireless and click on “NEW—FAQs on IMS.”

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