You may remember that I posted the URL for the BBC Radio 2 website in which they change a half doze or so "Brass band" tunes. Well, that same site ALSO has big band and jazz "forums". Some really great music being played in Merry Olde. Most highly recommended.
Another site that has fantastic "streaming music" is
http://www.ckua.com. This is the oldest "public" radio station in Canada and has an ENORMOUS library. It might not all be "straight ahead trumpet music" but you certainly can get your fill of just about anything you want from Classics to Comedy.