Hi guys - I have been looking for an answer on this and I even called Cingular but did not get an answer that I can feel comfortable with.
I have a Cingular Blackberry 8700c with unlimited personal Blackberry plan.
I bought an HTC "Trinity" PDA recently and installed Blackberry Connect software on the PDA and it is working. I also configured internet connection so I can surf the internet on the PDA with no issue.
The problem I have is the case. I have the $29.99 unlimited personal Blackberry plan and am wondering if I would receive a large bill for data usage? I called Cingular yesterday and the guy told me that I don't have to change plan. He did not sound convincing to me (by the tone of his voice I sensed that he just want to give me some quick answer and get me off the line).
Also, I looked on Cingular's web site and found that the unlimited personal Blackberry plan is longer $29.99 but $34.99. If I "HAVE" to swtich to the Backberry Connect Data Plan ($49.99) and later decided to to switch to the personal Blackberry plan, can I still get the $29.99 plan back?
Can any one explain how this work?
Thanks!

The $34.99 rate is the BIS plan on Cingular. The $29.99 rate is the same plan for lines with a voice plan over $39.99 in addition to the BB BIS plan. Basically what it comes down to is this: If you have a voice plan $39.99 or higher, Cingular gives you a $5 break on the BB BIS plan. I think you are ok, either way you go.

The BB Connect plan is for non-BBs to use the BB/RIM network, which is what you are doing with the Trinity. Or at least that is how I understand it. Not sure if you will be hit for a large bill, but it might get changed as Cingular is doing account reviews to make sure you have the "proper" dataplan. This is an offshoot of the Blackjack fiasco when no one knew what plan to use.

I would call Cingular, make note of the date and time and get the person's name who said you didn't need to change the plan. At least you have that to use as an excuse. It worked for me on the Blackjack.