Satellite phones' signal to satellites

[DocZaius]

I can see how the satellite has enough power to broadcast to the phone, but it's perplexing to me how the phone has enough power to broadcast to the satellite, especially when it comes to these small modern satellite phones. They don't seem to even be aiming the signal.

Just from my experience with the range of radio signals coming from relatively small devices (wi-fi routers, cell phones, etc...), I would think that it wouldn't be even close to possible to send signals to the satellite, but I'm obviously wrong! I am guessing that the frequency of the signal has a lot to do with it.

What am I missing? Anyone with a back of the envelope justification for this?

 

[thankz]

http://en.wikipedia.org/wiki/Friis_transmission_equation

 

[marcusl]

Unlike the geostationary satellites in 36,000 km orbits that provide trunk links for mobile phone networks, sat phone birds are usually in low Earth orbits only 500-1000 km up. At these ranges and with a large high-gain antenna on the satellite, the link can be maintained despite modest power and poor antenna on the handset.