Peugeot 306 CD /Radio problem?

I have just purchased a Peugeout 306 X reg. The fault i have is when i put the radio on, the message " PHONE " displays on the radio and i can't remove it and will not allow the radio to come on. I have not got the handbook for this so don't know the procedure to take it off. Any ideas guys? PS i believe its Peugeot's one that was built into the car because there is no make or model.