Lets get something straight here:
A T1, as Poontos so correctly stated, is not capable of even 200k/sec EVER. A single T1 will not get faster - you can have a 10mbps or 100 network but the T1 is still limiting you outside of the network. People who have said they've gotten 11k/sec on a 56k are probabaly victims of defective software in terms of tracking your speed. A 56k will not get more than about ~5-6k/sec, Its just impossible. I'm not sure if a modem byte has a start and stop bit...if not then you could ideally get about 7k/sec.
I had a friend who told me his 56k could ocassionally get 70k/sec. He was wrong, and living in dream land. I used to see mine ocassionally read 9k/sec on a download but it was the software reading the transfer incorrectly.
Back to question at hand my DSL once hit 491k/sec