Just a small technical point.
Data transmission speed is measured in "Bauds"
Baud rate is Bauds per second, i,e an acceleration.
Because of the confusion from this misuse, Baud has
been replaced by symbol/s - ITU-T Recommendation B.14 and
the new American Telecommunication Glossary 2000.
So "Baud rate" is really the same as saying symbols
per second per second.
I have never seen a data rate change slowly from one
speed to another. They always happen in discreet steps such
as 38,400, 57,600 or 115,400 bit/s