Audio file improvement

I have an mp3 recording of people talking. About 80 minutes long. The recording was made about 10 years ago while driving in a car, so there is background noise. More problematically, there is some loud electronic interference at times (I believe from a Blackberry) that at times completely obliterates what is being said and is so loud that it makes it unpleasant to listen to. I would like to improve the audio quality to the extent possible, and also to eliminate the electronic interference, or at least drastically reduce the volume of that interference so that it isn't unpleasant to listen to.