Hopefully you never need to, but every now again someone will order the wrong size SIM, or gets a new phone in between, or have the need to swap SIMs between devices.
Cutting your SIM down is a handy trick to know how to do when you don't have a professional SIM punch/cutter (although find a phone store nearly anywhere and they might have a punch).
I could do my best talk you through the steps, but I think it i
Peter Cain is the Founder and CEO of dataGO.co, a company committed to making it easier and cheaper to stay connected whilst travelling. You can find him on Twitter and Google+. You can also find dataGO on Facebook, Twitter, LinkedIn, and Google+ for all the latest info on local and roaming SIMs and data hotspots.