A few weeks ago comcast finally got around to banning my modded cable modem from their network (I think because i had used 1TB plus of bandwidth the last month). Being without internets and desperate, i added 3g service to my t-mobile plan so i could use it with my android.
I have a prepaid contract plan, so i pay in advance for any services i add, the data service is $25/mo from tmobile, and i had to pay 2 months worth in advance to activate it. After about a week i figured out a way back on to comcasts network (changing my cable modems mac address), so i canceled the 2nd month of data service that i paid for.
On the 20th my new bill cycle started and my 3g internet service should have ended, but it was still working just fine.
Knowing what i do about cable modem hacking, i figure the reason my service kept working is because just as with comcast's network, t-mobile's 3g network is active on phones even if you dont actually have the service. The DNS comcast gives to valid subscribers differs from that of non-subscribers. Comcast uses a DNS redirect to prevent unsubscribed users from accessing any pages outside of the 'sign up for comcast' page, and t-mobile seems to do the same thing. But if you have the old (subscribed) DNS working on your phone, it will stay that way until you shut off the phone.
At least thats my best guess... Even though i have a developer phone, i'm not sure how to (or if its even possible) change the DNS manually on the 3g network. So to get free service i'd still have to pay for at least a months worth, and keep my phone on forever (which is kind of hard due to its crappy battery life).
But I thought I'd share these findings with my fellow phone losers, and maybe someone else can do more with it. Keep in mind i'm not sure how well this would work on a post pay account, since they may or may not actually keep track of your data usage and charge you after the fact.
