First, determine mo una kung ano ang hindi nagpa-function sa phone mo, if the transmitter section or reciever.
For reciever, go to setting, network and set it to manual not auto. If phone found network, then reciever is ok. Pag walang makitang network it means reciever is not functioning.
You can check TX by pressing # then call button. Go to a nearby radio or TV, kung may interference sa TV or radio coming from your phone, then TX mo ok, if not Tx section is not functioning.