we've got a efw mobiles in our company and, as happens sometimes, some of our, how shall i put it, more foolish drivers ranup bills on them by sending theses naughty text messages to everyone

they got docked their wages for this but now we have other drivers in to replace them, the naughty messages are still coming throug on the phones

the problem is that they don't originate from a number source, only a name comes up when youtry to get any info from them

the question is, how do we stop them from coming through?

anyone else had this?