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T-Mobile @Home and UMA: It Works

While it’s been kind of a rough week workwise, with the announcement of Nokia selling off the Security Appliance business, I did get a couple of new phones to play with: The Nokia N96, which I will review later, and the Nokia 6301. The latter phone came as part of signing up for the T-Mobile @Home service. You can read my review of the Nokia 6301 over on Joy of Gadgets.

Meanwhile, on this blog, I’d like to give you an idea of how the T-Mobile @Home service works. I kind of know how Unlicensed Mobile Access works, having taken a rather technical class a couple years ago about how it all works and how to configure a now non-existent product to support it, but I never got to play with a commercial implementation of it.

Now with the Nokia 6301 in my hand, the theory I learned a couple of years ago meets practice. And you know what? It works.

I’m not going to bore you with a lot of technical details–some of which I’ve probably forgotten anyway. But what I will say is that UMA basically takes the GSM protocol and stuffs it in an IPSec tunnel like a typical work laptop would use to connect to the corporate network from a remote location. The authentication for this connection is based on your SIM card, which makes it dirt simple to configure into the phone.

The upshot of the way UMA works is that when you’re on WiFi, all of your connectivity goes over it as well: SMS, GPRS, and voice calls. Your data applications don’t have to be aware that the underlying transport mechanism is changing from WiFi to the mobile phone network. They just work, just like the voice calls do.

Of course, the reason the carriers are doing this is because building towers is expensive and fraught with governmental red tape. Even when the towers are there, getting coverage indoors is a problem. For an extra $10/mo, T-Mobile @Home gievs you unlimited calling while you are connected to a WiFi hotspot, whether it be at home or one of T-Mobile’s hotspots. Your phone will automatically connect to a T-Mobile hotspot if it sees it.

Of course the downside to the way UMA works is that the phone has to work a bit harder to monitor both the GSM and WiFi radios to be able to handoff the call between the two networks without skipping a beat. Forum Nokia estimates the talk time for the Nokia 6301 at 3.5 hours. I imagine lots of GSM to WiFi handoffs bring the battery life down a bit from that estimate.

While you can certainly do calling via WiFi using services like Truphone or iSkoot, UMA provides a completely integrated one-number experience. Truphone comes awfully close, as it even supports SMS over WiFi, but the problem with Truphone–or maybe the benefit, depending on your druthers–is you’ve got another telephone number to worry about.

For normal people, T-Mobile @Home is a great way to go. It’s completely transparent and works the same way whether it’s WiFi or GSM. It’s certainly not without it’s issues–particularly in the handset choices–but it is a viable option.

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