I was sent this, and pass it on in case it's true (probably is; I've heard of similar things), but sometimes these are put around as alarmist scams themselves, but better safe than sorry..
Please pass this to everyone you know with a mobile phones
If you receive a phone call on your mobile from any person, saying that he or she is a company engineer, or telling that they're checking your mobile line, and you have to press #90 or #09 or any other number, end this call immediately without pressing any numbers.
There is a fraud company using a device that once you press #90 or #09 they can access your 'SIM' card and make calls at your expense.
Forward this message to as many colleagues, relatives and friends as you can, to stop it.
Many thanks for your time regarding this matter, take care and regards.
Police Constable/Crime Prevention Officer
Ext 496696 (Internal)
01524 596696 (External)
Email PhilCorris@lancashire.pnn ..police.uk