This is a hoax. The following is full text of one such email:

Dear All, "Subject: Mobile phone virus - ?UNAVAILABLE!?

This is for real, this is an early warning.... If you receive a phonecall and your mobile phone displays: ?UNAVAILABLE!? on the screen (for most of digital mobile phones with a function to display in-coming call telephone number), DON'T ANSWER THE CALL. - END THE CALL IMMEDIATELY. IF YOU ANSWER THE CALL, YOUR PHONE WILL BE INFECTED BY THIS VIRUS.

This virus will erase all IMIE and IMSI information from both your phone and your SIM card, which will make your phone unable to connect with the telephone network. You will have to buy a new phone.

This information has been confirmed by both Motorola and Nokia. There are over 3 million mobile phone being infected by this virus in USA now. You can also check this news at the CNN web site. Please pass this on to everyone you know with mobile."

Remember, hoaxes cost companies - and people - time and money. Please do not forward them to others.