You can try this site..

http://myspeed.visualware.com/server...pdetective.com

Note that there are a number of different tests you can do.. I've linked to the quality test.. that is probably the best one to do first.

Also, I'm assuming you have a dry loop line for your DSL which means that a phone couldn't be used on it anyway since it isn't set up for one.

And finally you may want to use a different DNS server as a test.. here's instructions on how..

https://developers.google.com/speed/...dns/docs/using

.. to use Google's free, public DNS servers. It's actually a lot easier than it looks at first glance.
Their DNS addresses are 8.8.8.8 and 8.8.4.4. Select IPv4.. don't worry about IPv6.

here's another tutorial on how to do that..

http://www.labnol.org/internet/setup...servers/11439/