Subscribing to channel not in your plan

[mcc3]

I wish to get one channel (Smithsonian) that is not in my "Prefered" plan.  When I enter the channel number the screen says I am not subscribed to that channel and gives me the option to subscribe.  Does anyone know exactly what will happen if I subscribe, i.e. does it merely bump me up to a higher cost plan or does it let me get the channel for a (lower) fee on my current plan?  And, if the latter, does the subscription expire  or remain until I wish to unsubscribe?

[Edg1]

It will upgrade you to the next plan. As far as unsubscribing I don't think there would be an issue. You can switch between TV packages without changing your contract. 

[Pluggo]

So, if I hit OK to get one more channel I am not subscribed to they should provide at least a couple more screens, telling me how much it will cost, what other channels are included, the name of the new package and a chance to back out at any step along the way until I hit a final confirmation button. Am I right?