alright...i've figured out what's going on here. i just purchased a pair of Jabra C220s from Best Buy to compare with the pair that I received from the seller on eBay, and there are some differences:
first off, the pair from Best Buy WORKS! as some of the users have posted, the actual C220s from Jabra (in package) work properly...when i hit the little black button on the mic part, the music pauses, and when i hit it again, music resumes properly...in both ears.
secondly, there are minor appearance differences...on the little clip, the word Jabra should be present...on the pair from Best Buy, its embossed, but still black letters. on the pair from eBay, they are painted on, in white letters.
thirdly, the model numbers are different. eventhough they are both Jabra C220s, the ones from Best Buy are model # 100-37630000-02, and the ones from eBay are model # 100-37650000-00.
and fourthly, the 2.5mm plug is different in shape. the pair from Best Buy is a straight plug, while the pair from eBay is a right angle plug. I've posted a pic below showing the difference between the two plugs.
i dunno if the ones from eBay are knock-offs or just a different batch, but if you just want a pair of headphones and don't mind that the little black button doesn't work properly, then the price that the eBay seller has it for is great...but if you want one that works properly, gonna have to buy one from Best Buy (or some other retail place...), or atleast make sure its in the original Jabra packaging.....hope this helps and clears up the issue