magicjack is interfering with my micphone

[need help_10]

I've had magicjack for awhile now.I recently when out an brought some headphones/w mic,to talk and listen with others.
my problem is i cant talk with them because when i plug it in magicjack interfers with it.
when i dial an number or someone calls is the only time the headphones works.
i figuring the configerment are mixed up can anyone help me with this