This video will show you how a ping looks like, how long the smart phone broadcast this signal and how much time will pass between one ping to the next. In this video you will see that the blackberry smart phone pings the nearest antenna every minutes, and the communication takes more than 10 seconds!
Each cell phone sends a communication signal, "Ping", to the nearest antenna every few minutes. Every smart phone emits RF (electromagnetic) radiation when sending or receiving an email.
Manny people use a smart phone as a working tool, they carry it with them all day long and use it to send and receive lots of emails and SMS.
When you carry your mobile phone with you all the day you are exposed to this RF Ping signal. When it is a smart phone and you use it to receive and send emails you are exposed to even more electromagnetic radiation.