Yup, mine does that also,.. but its easy to fix.

Basically its cutting in and out cuz other running apps on yer PC are taking away from the MJ. at least that was my prob.
it seems they don't have the apps priority set right. it defaults to NORMAL. which is simply not enough for this thing.
SO.... load up task manager, hit the PROCESSES tab, then find MAGICJACK.EXE, and right click on it, then SET PRIORITY from NORMAL to anything higher.
(NOT REALTIME)
(
I have found HIGH, to be perfect):idea:
This should fix all yer problems with sound issues and hiccups and things like that. It was amazing to see how much it helped!
Now to anyone that's gunna say my PC isn't fast enough, and so on. that's all BS. my system is plenty fast enough to run this thing.
I've got a P4-3ghz, 1.2gig ram. WinXP.
I have tested this same fix on various other peeps systems and it fixes all there probs as well.
So, there ya go. Good luck!
-Rob