Smartphones That Let You Make Phone Calls over Wi-Fi Connection or Mobile Network: Introduction to UMA

7 November 2006

When major phone manufacturers include both Wi-Fi and mobile network connectivity in their smartphones, there's got to be a reason for it. There are two major differences between Wi-Fi and mobile network technologies. Wi-Fi introduces low-cost, or free, broadband-speed Internet access, but doesn't allow you to move outside the hotspot's signal range. All mobile network technologies, on the other hand, allow moving from one place to another without losing connection; however, the data transfer speed is slower than with Wi-Fi, and you have to pay for the connection.

What if you could combine Wi-Fi and mobile network technologies so that, when you are moving, your call would be routed through the mobile network? Then, when you come home, your phone call would pass through your Wi-Fi access point, without interrupting the call. That's exactly the brilliant idea behind UMA (Unlicensed Mobile Access) technology.

Say that you are heading home from the shopping mall. You are in a car, sitting beside the driver, yakking on your phone. As the journey progresses, your phone jumps from one cell tower to the next cell tower from time to time. You don't realize it, because it is an automatic operation between the phone and the network that covers the cell towers. You come home, open the front door and step into the range of your Wi-Fi signal. If you have a UMA phone, it automatically switches from the mobile network (GSM, or UMTS network) to the Wi-Fi signal from your home broadband connection.

You pay for your phone calls in the mobile network as before, but the charge is different at home, where your phone call goes over your broadband connection. Now, you already pay for your broadband; but if you use it for UMA phone calls, you may have to pay extra to your phone service provider. Usually there is a fixed price per month for UMA service.

If it's your bad luck to live in a place where mobile network coverage is patchy or non-existent (when you are indoors, that is), you are a prime candidate for UMA. UMA solves your dropped call problems at home…well, at least within 30 feet / 10 meters from your Wi-Fi access point. Phones can lose the Wi-Fi signal even sooner if there are any obstacles, like heavy walls, between the device and the access point.

Nonetheless, you don't have to worry about costs when you are making UMA phone calls at home, because typically it is included in a flat rate service for the Wi-Fi part.

Even if you can't get UMA service, you can still enjoy the advantages of high-speed Wi-Fi communication on a smartphone. If you get a Wi-Fi phone, you can keep checking for news on the Internet in case Skype manages to introduce its software for smartphones before your service provider offers UMA.

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