with a little search magic, you could probably find your answer easily at the ATT forums on howardforums.com. It's a great site.

Correct! I posted to soon!
Howard forums has a great but long thread on tethering with AT&T
here

Long story short - the media net total at $15/month works fine with tethering if your phone supports and if its not a smart phone you got from AT&T (where they charge you the $30/month). There may be restrictions in the future on ports etc. but that can be dealt with. I'll see what AT&T offered phone still have tethering (I'm likely to go with the nokia 6650 if I do AT&T)

Just for completeness:
I picked up a nokia 6650 the other day. I was looking mainly for a 3G phone that could fly under AT&T's or T-mobile's smart phone radar, was inexpensive, and played nice with the n800. The 6650 seems to fit the bill. I kicked around an older unlocked nokia, but via my wife's company I got the phone for free (its about $70 after rebate with a 2 yr contract).

Its sad how little most AT&T store reps know about this phone. Yeah its branded, which was discouraging at first, but its still got S60 and enough tweaks to be found around the symbian world to get rid of the majority of AT&T annoyances. Its has an amazingly quick pick up with its GPS (A feature a store clerks said would be disabled unless I use AT&T's nav), and works well as a walking city GPS with google maps or nokia maps.

In downtown Boston I get about 800 kb/s and average 500-800 around the city on the $15/month unlimited medianet plan. Tethering was a snap, and I can stream audio, last.fm, and video on the go without an issue (cept on the subway of course ).

I use Verizon service and have tethered both a Samsung SCH I760 and, currently, a Samsung Omnia. The Omnia gives greater download speeds as it is 3G, where the I760 was the lesser EVDO standard. Check Howard Forums Verizon sub board for threads about ICS CABs and WMWifirouter. These CABs are free and do not cause a charge to your Verizon account. The Omnia is a great Windows PDA phone, by the way. I need to add that I have the $29.00 Data plan and an N800.

You said your firmware version for the TM506 still allows tethering. Which fm version number do you have?
Thanks!

Okay, I have messed with the settings on the n810 for an hour and a half. Can someone please post the correct settings for connecting using the TM506.

Connection Type: GPRS
access point name: internet2.voicestream.com
Dial-up number: *99#
username: blank
password: blank
prompt password: unchecked

Proxies: all blank
IP Addresses: auto retrieve IP address
Auto Retrieve DNS: blank
Primary: 66.94.9.120
Secondary: 66.94.25.120

Allow plain text login: checked
Use PPP compression: checked

This is my best guess, but it keeps failing to connect! Any advice???

I am connecting using the t-zones plan. Here are the differences in my settings:
access point name: epc.tmobile.com
Dial-up number: *99***4#

Also, I am using the opendns dns IP addresses.

Since you have the internet plan. you may want to keep your APN the same as what you have. THough, I think the epc one will work too.

I think your problem is the dial up number. with the tm506, you must specify the connection profile number. t-zones is 4. the internet plan is probably 1 or 2. There's only five of them, so I would run up the list until you find one that works. start with *99***1#.

I hope that helps.

Thanks for the suggestion! What worked was changing the APN to epc.tmobile.com. Also I use either *99***4# or *99***5#. 5 seems to be faster, which would make sense if 4 is t-zones as you said.

Here's the odd thing, the APN internet2 works tethered to my laptop like a charm, along with the DNS addresses I included previously. I guess I assumed that would work as well.

Regardless, thanks again!

Has anyone gotten the N810 to use the TM506 as a GPS? It shows up under my settings for picking the GPS but never sees anything.

Is this even possible?

I've been running some speed tests with my T-Mobile data plan tethered to my TM506. I used three different settings and ran each one six times separated by twenty minutes each. Your experience might differ but here they are using the website of: speakeasy.net/speedtest:

Using APN: epc.tomobile.com, DUN: *99***4#:
UP:619 DOWN:92
UP:677 DOWN:96
UP:766 DOWN:95
20 mins later:
UP:618 DOWN:114
UP:549 DOWN:102
UP:723 DOWN:105

Using APN: epc.tomobile.com, DUN: *99***5#:
UP:597 DOWN:57
UP:567 DOWN:86
UP:575 DOWN:53
20 mins later:
UP:482 DOWN:88
UP:594 DOWN:80
UP:535 DOWN:102

Using APN: wap.voicestream.com, DUN: *99***4#:
UP:629 DOWN:99
UP:570 DOWN:failed
UP:638 DOWN:failed
20 mins later:
UP:806 DOWN:failed
UP:623 DOWN:failed
UP:683 DOWN:failed

My conclusion is that using APN: epc.tomobile.com, DUN: *99***4# is the best route to go but these are such small variances that I don't believe there is a clear choice. Anyways, I hope that it helps in some way.

And also, just to re-ask, has anyone successfully used the GPS in the TM506 as an external GPS for the tablet?

Ummm, in the above examples, please swap UP/DOWN as the download would always be faster than upload.