How are messages sent between mobile phones?
Your mobile phone transmits your message to the nearest antenna (mobile phone mast) as a high frequency radio wave, around 1GHz. The antennae are connected to central hubs and the message will be sent there by underground optical fibre cables. If your friends phone is on, the central hub will find out which antenna it is closest too and send the message there, again using underground optical fibre cables. The antenna then sends the message to the phone using radio waves. If your friends phone is off, the message will be stored at the central hub and stay there until your friend chooses to retrieve it.
