I couldn't notice (in Germany we call it) 'pumping'. I don't think it's caused by auto-leveling. OTOH the pulsing noise might be caused by a strange limiter because of some peaks, but try to reproduce such a sound using LADSPA limiters, compressors on your computer. Ok, it might be caused on the analog domain, anyway, for analog limiters and compressors it's the same. Regarding to a 'half level' recording. If the user hasn't got the equipment to reduce the level, a pocket handkerchief might help (unfortunately it would be a pass filter too ;). Because it's a telephone, it might be all kind of strange noise. I guess we all know the sound a cellphone could cause to radios etc.. How do they prevent that such noise has no impact to the cellphone's audio itself?