Weak EM waves connect the cordless handset to the base which is hard-wired to the phone network. Stronger EM waves are used to connect cell phones to towers that may be very far away.
Work Step by Step
Cordless phone handsets encode sound waves into an EM signal that is sent to the base in your house, which is physically connected to the phone company’s network. These EM waves used by cordless phones are relatively weak; They don’t have to travel very far. Similarly, cellphones send/receive information to/from cell towers, which could be kilometers away. Cellphone transmitting and receiving antennas need to use higher-amplitude EM waves and/or be much more sensitive than cordless phone handsets.