Android phone that doesn't trigger rate increase on AT&T?

[Superorb]

I've still got 11 months or so left on my 2 year family plan with AT&T, but I'd like to buy an android phone now and sell my existing Samsung Impression. What is the cheapest Android phone that will not switch me to the smart phone data plan? I'm currently on the $15 unlimited dumb phone plan. The G1 looks cheap, but will an unlocked one trigger the plan change with AT&T? Is there anything else I should be looking into?

 

[HustlinDaily]

You need to find a phone which AT&T probably does not have the IMEI # for in their system. Probably one from overseas which isn't very common here.

I have an Acer Liquid (got it for around $360, currently selling at around $340, isn't expensive for an unlocked smartphone, especially one with pretty good specs) and am on a cheap unlimited medianet data plan (have been for around 7-8 months and AT&T has yet to catch me, and I use about 1GB/month on average).

G1 is nice but Rogers in Canada being connected to AT&T here, might not be a good idea (tho Acer Liquid E, one step up from Acer Liquid recently released on Rogers, and I have still yet to be bumped up to the expensive data plan).