Something about which I know very little.
My daughter has recently bought a new Siemens phone - one of those which takes pictures. The SIM card from her old Nokia phone (Virgin Mobile) seems to work in the new phone but the SIM card from the new phone doesn't seem to work in the Nokia. Any reply gratefully accepted, even if it appears obvious to you.
The Nokia is probably locked to one network so if the sim is of a different network it won't work unless you get it unlocked. This can be done at any phone shop or probably a market stall. hope this helps.
better yet you can download an unlocking calculator for Nokia phones locked using the DCT4 method: do a search on google for "Nokia DCT4 Phone Unlock" and you're bound to find it. Not all Nokia models use DCT4, but the software tells you which models it caters for...