Delivering VoIP over Mobile Wireless

Both VoIP and mobile wireless broadband are relatively new technologies. With the invention of 3G wireless data network – an opportunity to make free or near free calls from your VoIP phone had become more of a reality than a concept. The war between operators of cellular networks and VoIP providers has ended in an amicable truce with the carriers finally realizing that the bulk of their revenues will be coming from data usage and shifting to the usage-based billing model for their data plans. VoIP Hosted PBX users have been jumping on the bandwagon by making calls over Wi-Fi or the carrier’s wireless data connections on all kinds of smart phone platforms.

VoIP service providers, while reluctant to even mention 3G mobile data network as a somewhat reliable means of enterprise VoIP communications, nevertheless are coming to accept the fact that businesses begin to realize the advantages of readily available mobile networks in order to benefit from truly geo independent voice service. There is even a new term for it: Vo3G which stands for Voice over 3G.

Meanwhile the industry is toying with the concept of Fixed Mobile Convergence – a technology that would allow a seamless handoff between cellular carriers, VoIP and PSTN over Mobile, WiFi and Fixed Wireless Networks all of which are currently operating in their own separate realms. With Fixed Mobile Convergence, an individual would be able to be on a cellular phone call during the ride into the office and once they arrive at the office, they would not have to continue the call on the cellular network, but would be able to seamlessly “hop-on” to the office wireless network. This could also be extended to allowing a user to use multiple devices on multiple networks while still being on the same call.

These innovations further complicate the ability of adhering to any type of service quality agreement offered by Hosted VoIP service providers. Not only because VoIP call is traversing a 3rd party network but also because mobile wireless xG networks have the ability to automatically transition to slower EDGE where 3G is not available or because xG network are notorious for becoming congested and overloaded at times. Another factor diminishing voice quality has to do with the medium itself. Wireless technology is subject to typical RF issues such as interference, variety of modulation algorithms, signal strength, signal to noise rations and many others. But in spite all this: less than perfect technology in less than perfect environment continues to deliver voice and even video calls and many business companies are giving their own answer to the centuries old choice of “availability vs. quality”.

So how is the call quality impacted by the use of Voice or Video over 3G ? Well, the answer to that depends on where you are and what you do while you are making this call. Not all 3G calls are going to be the same. And there is an increased likely hood of dropped or lost calls, choppy, latency and jitter due to packet loss as a result of the dynamics of calling over mobile IP. On few occasions now I had tried to use my iPhone 4 with SIP soft phone to place video calls to my dad who lives overseas. The voice and video quality were surprisingly good until my car started to move. Then video slowly began to lag behind as both jitter and latency increased. Voice however remained reliable throughout the entire 20-minute conversation. Video never caught up even after I pulled into my garage well within range of my home Wi-Fi access point. This part was not a surprise. What was surprising is the amazing sense of telepresence on that video call right there in my car with someone who was thousands of miles away in a different time zone.

But this or any other example can not be used as a benchmark. The call quality with Vo3G must be expected to be a hit or miss depending on wireless signal quality (location), utilization of carrier’s wireless network cell and numerous other factors.

At least one of our customers – a limousine company based in Chicago had decided to take their chances in rolling out soft phones to their drivers. The result of this, bold, by all standards, move remains to be seen. They certainly do have my attention and I will blog about their experience in the future.

Bottom line: there are arguments for and against Vo3G (or VoWiFi) but for me – VO3G is a step towards making a dream come true.