DECT 6.0 is a marketing term. It's just DECT at 1.9 GHz for the United States. Given that though, you can tell folks your home phone is 3G. They'll look at you funny, but you can say it.

DECT is a wireless technology

http://en.wikipedia.org/wiki/DECT#DECT_6.0

You can use Bluetooth headset with tablet I believe

Paired with VOIP (SIP) the N8x0 works pretty well as a phone.

Now I'm traveling in Finland and use N810 exclusively to call home and relatives using hotel free WiFi. Call quality is very good, if not excellent. I do use the N810 as speakerphone and it is very good, as was already pointed out earlier in this thread.

As a second application, my mom was planning to get a laptop with 3G USB dongle to get internet access while not home... Since she already has a N810 I told that they can just buy a 3G capable phone and a new voice plan with data. They do not need a laptop anymore. So that happened last weekend, we bought her a phone (Nokia 6220 Classic, pretty nice phone!) and cheap voice plan with unlimited data (cheapest/slowest 384kb/s). It paired with N810 flawlessly. Now we have made some VoIP test calls and it works fine. However, there is some problems in one area which is at the edge (no pun intended...) of the 3G coverage area where it drops to EDGE... then the upstream data speed is a bit too low for acceptable voice quality. But the nice thing is that the phone can be placed next to the window where it can pick the 3G/3.5G (HSDPA in this case) network signal while the N810 is connected via Bluetooth and few meters away... So in this sense the separate phone solution is a lot better than a USB dongle that would need to be hard wired to the laptop. Also, I was also able to share her internet with my N810 as well. (But of course it didn't work at the same time... I tried... )

How well does the N810 work as a phone (via SIP or whatever) when held against the ear as a normal phone? Where is the microphone, in other words, which way up should it be held?

If I was going to use this thing as a phone I would prefer to hold it to my face like a normal phone rather than use a headset or as a speaker phone.

The microphone is behind the small, pill-shaped hole on the bottom edge of the N810, under the desk stand, next to the external card slot door.

Thanks. So not really is a great position if holding the device up to the face, I guess. Let's hope the new hardware is better is this respect.

It doesnt really matter where the mic is positioned. The pickup from the tiny mic is great on the N810 and even if I just place it on a table I can talk from across the small room and my voice is still audible clearly to the other users.

So if you hold it to your ear, it wont make any difference at all if the hole is nearer or a few inches away from your face. It doesnt matter at all what with the great pickup from the mic. Its not like a cell phone mic - which is calibrated to have a near field pickup only.

This mic can pickup your voice from much farther away than a cell phone.

LOL...I had no idea this thing had a built in mic...I always figured you had to plug in the headphones with the built in mic...

The problem with using your tablet as a phone besides other issues... unless you have headphones, everyone is going hear your conversation thanks to the speakers.

Yeah I guess there would need to be a mode in whatever software you are using that would lower the volume and only output to the speaker nearest your ear, when holding the thing up to your face rather than as a speakerphone.