I'm new to the Forum, i've been a lurker for a long time of all the Android Forums, and figured i would shed some light on this issue since i see alot of posts from various other forums, including this one. I used to work for sprint as apart of their leet network team and dealt with these kind of issues. most of the time when you call Customer don't care they will throw you around because no one really knows anything about this issue or how the network actually works.
1st of with sprint there are two usernames and passwords associated with the data network. You have your "NAI" (Network Address Identifier). It's similar to what you would use if you were on the old school AOL to login. the phone will automatically have it stored, and when it hits the cell tower it passes the information along to the AAA server (Authentication Server). The Username consists of you
username@sprinpcs.com (ex.
joebob93@sprintpcs.com). You can find the username by going to your phone and typing in ##3282#, and select view mode. The password isn't as easy to find, you can use some software to find it, or if you're really really lucky to get into a Technical support rep that knows a thing or two they can look it up for you, but you have to be very convincing you need it.
Now when connecting your phone and selecting the teather phone option and hooking it up your computer. You're going to get "Error 67: vision username/password is incorrect" or something to that affect. Her is where your second username/password comes into play. Sprint calls this PAM (Phone as modem) with their standard rate plans, due to some idiot that created the phone plans they made it pretty darn hard to add the Phone as modem plan for this phone, and most of the time they will tell you it's not possible. When in reality it really is possible to add the plan, but will cost you out the bum for it. Last time i checked it was about 30-40 a month. And it's not unlimited data, but caped at 5 gigs a month. The second username/password is going to be similar to your NAI, instead it will be
username@pam.spritnpcs.com. and the password is different as well. Reason being is because it goes through it's own AAA server on the sprint network.
the 3rd party apps that people install typically the root app for the phone that creates it into a wireless hot spot actually reroutes the data, and uses the NAI and routes it through the phone as though you were using the browser.
I've played and still have been playing around with trying to correct this issue for the new hero 2.1 software, but have no luck.
So unless you really try hard and make alot of calls to sprint, and get one person that doesn't know the rules or what their doing you won't get that teathered option to work. They did say they were thinking about adding it into the billing options when i left there in jan, but never made it so.