coding in hexadecimal the phonenumber

I am initial in the programming javacard, and my work has to make is to program a chart SIM GSM for the sending of SMS to waiter SMS of the operator in place to number 555.

I read documentation, until there that goes a little because I still read, but I am blocked not to include/understand a problem, it is that to convert number 555 into byte. Somebody can help me to explain to me how to make and especially whom 0?F?represents

You can write to me with my email: mudibu01@yahoo.fr

Thank you very much.

[531 byte] By [visionsofta] at [2007-11-26 19:48:02]