I have a fresh 3 Mifi SIM (for Huawei E586) which I want to activate ready for our trip to France this week. I've used one before but can't quite remember the proceedure. My Mifi unit is remembering the last SIM data details which do not seem to update when I put in the new SIM. It is telling me that I have used 900 MB and have 100MB left (it was a 1GB Sim). Will this update to show me that I have 3GB available or do I need to register the SIm online somewhere?