You didn't shoot any birds or squirrels off of the phone line with it did you? Or, it could be Wolf ammo. It has been blamed for everything else, I could certainly see it causing static on your phone. Or, you could try putting a little grease on your buffer spring. Oh wait a minute, that's for sproing, not static.
OOH OOH, I know what it is...you have a mini-Y on your M4 and you don't use hearing protection!!! Yeah, that's the ticket!