What are dual Sim cards?

I have just bought a pre-paid Vodafone but the rates to call home (America) are still very high (.75 Euro a minute). I was curious as to what is the beneficial (cheap and effective) way to call home. I have heard of really low phone cards and was wondering...

hiya i just got my blackberry curve 3g fixed. everything else is fine except the blackberry will not accept any sim cards. it still says the sim cards name but i cannot use the internet, send or recieve text messages, make or recieve calls nor can i...

Many other mobile phone makers allow dual SIM cards; why is Nokia so much against this?

What to do with expired SIM cards? I have at least 3 ( three ) used and expired mobile SIM cards and I cannot figure out as what to do with it. Should I throw away or burn it or break it before disposing?

I have a Samsung BeHold SGH-T919 unlocked phone,I need to know what other SIM cards would work with that phone with a no-contract plan? I was with Simple Mobile but my phone was off for more than thirty days & they told me that I had to get another...

Based on a phone conversation with a (assumed clueless) Verizon customer support person, switching sim cards can improve the ability of the phone to switch from 3G to 4G LTE.  Does this make sense? Initially we were thinking no, but maybe Verizon stores...

Actually, why did it not happen so far? Every part in a cell phone gets smaller whereas the SIM card remains the same since 1991. Apart from Apple's incremental steps to shrink the size step by step, there's no greater innovation which would abandon...