phone technology has moved on,
The major change in phone technology since the early days is that the RF output power has reduced considerably however; it is proportional to the received signal. This is a means of conserving battery power. The weaker the received signal, the higher the power of the transmitter, so when conducting tests, you will get different results depending upon the reception area you are in. You may have noted how, when leaving a phone unattended for a long period, the battery life is vary variable, and longer in a good signal area