DSL connections are usually asymmetric (ADSL), meaning only a small portion of the connection can be used for upload and the rest is download dedicated. That means for a 3Mbps you can download with 300kb/s which is ok but can't upload with more than 40kb/s causing broadcasting trouble with video streaming applications.

The distinguishing characteristic of ADSL over other forms of DSL is that the volume of data flow is greater in one direction than the other, i.e. it is asymmetric. Providers usually market ADSL as a service for consumers to connect to the Internet in a relatively passive mode: able to use the higher speed direction for the "download" from the Internet but not needing to run servers that would require high speed in the other direction.

A high end 6Mbps ADSL usually has only 512kbps for upload. As 1 byte = 8 bits, that allows a maximum of 64kb/s of upload in best conditions which is just enough to broadcast with medium quality if you don't have other software using the internet connection at the same time.

A basic 1Mbps connection with 128kbps (16kb/s) upload makes it impossible to broadcast. Even a 2Mbps connection with 256kbps upload (32kb/s) is not enough for broadcasting a decent 50kb/s video stream. At least 512kbps upload is required. We recommend a 768kbps upload connection for good broadcasting conditions. On ADSL that's usually available for 8Mbps or higher plans.

Test your UPLOAD speed on these websites:
http://www.speedtest.net/
http://www.changeip.com/locationfree/support/speed.asp
http://www.dslreports.com/stest?loc=2

When you plan to broadcast video for consultations, conferences, events make sure you get a connection with good upload speed that can do the job.