Maybe it has something to do with the adaptive power controls on most modern phones. They throttle back once the connection has been made. The only other explanation I can think of is if the phone is perhaps tethered via a USB connection. That might drop the levels way down since it's wired and not wireless.
I'd do a little light reading on SAR/EMF here-
Hi, loving my new motorola defy, but came across the fact its got a huge sar level (1.54) 'when near ear or worn on the body' but a really low (0.16) in data transmission mode'
Have searched about, but can't find a definition of what this is.
presuming that the 1.54 is when you are talking on it, but is the 0.16 'data transmission' when its still in 3g/wifi using the web range ?