HRMs - high readings/cell phone interference?

Four_Leaf_Clover

Just got my new Polar FT4 and took it out for a spin. I am doing C2K and use my iPhone for music, Get Running (C2K app) and Mapmyrun (measures distance and route). I think I might be getting interference from the phone in the HRM. Or perhaps it is just reading high? Even when I first put it on (before I had my iPhone on me) - it just seemed like a really high reading (90 bpm). Once I was doing the runs - my heart rate was going out of my training range repeatedly.

I am concerned that the HRM is off (too high in bpm) - which would overestimate my calories burned. Either that or I worry that my heart rate is continuously out of the training range (I am out of shape).

Any suggestions for calibrating the readings or helping with the potential interference from the phone (I carry it in a waistpack)?

Thanks!