How do you change the modems serial number?

[Console Master]

i read on unlockers that NTL had detected cloned modems by looking at the serial number. so how do i get the modems serial number and how do you change it? ive got 100, 120 and 200 on my desk

 

[L33tpL4y4]

Theres no point, how you going to know the cloned macs SN?