wat kind of antenna should use?

i'm using FM 868MHz transmitter and receiver module for my transmission. As i know, our handphone also operate at frequency near 868MHz,may i know the frequency of handphone? wat kind of antenna should i use? can i use the handphone antenna?

Yes, you can use a 800MHz cellular antenna.
Some examples:
http://www.ethertronics.com/assets_f/GA%20Datasheet.pdf
http://www.galtronics.com/cellular.html