GSM SIM CARD number conversion

Hi Guys,

The problem I have is that I would like to take a sim card, read the
numbers from the sim card ,then to each number add a least cost
routing path

for example

0161 838 76363
would be converted to
252**0161 838 76363

Then write it back to the sim card.

Where do I start? Is there any source code examples of a similar
thing on the web using a usb reader/writer? Even the smallest bit of
info would be greatly appreciated.

Thanks in advance