Originally Posted by scotth
SIM cards and phone numbers are like IP address's - they can only exist in one place at a time....
Not always, on Vodafone here in the UK we have a product called "multi-sim" which allows you to have 2 sim cards with one phone number! Why - we'll its mainly designed for people with fitted car phones (those were the days) .. or the fancy car stereos with mobile gubbins and sim card holders.
Hop in the car, press a few buttons and any calls go to the car phone..hop out of the car press a few more buttons and calls go to mobile...
IIRC there was something smilarish on T-Mobile in Germany..