Basically, as the title implies, I am wanting to make someone's audio sound as if it is on a telephone, such as someone calling into a radio talk show. I have played around with various filter combinations, but have had little luck. I am using Adobe Premier (6, I believe...do not know right off hand). Anyone have any suggestions (other than, ya know, buying new software?)

there was actually a recent thread on this, it is very easy. Apply an EQ to the track and place shelving EQ's at 800hz for the low end and 3000 Hz for the high end. Then apply a standard soft knee compression to the track. Voila. The AM radio effect is the same except with cutoffs at 500 Hz and 5000 Hz (roughly). Use less compression on the radio than the telephone. These settings work because this is exactly what happens to the signal in a telephone and an AM radio transmission. Here is a radio call in show using these exact principles:

http://www.testpilot111.com/newscast.mp3

Thanks! Had no clue about the recent thread...usually I use the search feature, but that completely slipped my mind today when I posted. Will definitely give this a shot.