Had the same problem with my MJ when i used it with an regular handset with call id built in and so on, the MJ draws a certain amount of current available at the USB its hooked into, for most comps its somewhere around 500ma as the max power at the USB, and the pc usually sets it at somewhere around 100ma or less, however the phone draws current as well your pc sees this draw and wants to turn the device off to preserve power, this is very clear on some pc's as it results in horrible call quality as the available power is spread thin over the MJ and the phone hooked to it corded or cordless. It's also very pronounced on portables esp netbooks. Solution: buy a reputable self powered USB hub some are cheap at under $20 all the way up to $50 or so. Besides the constant stream of power that doesn't have to come from your pc, even though it must be plugged into the wall socket via an adapter, the extra USB ports have come in handy and the power is more consistent and I can use it to charge several devices at one time with great results. The best one for my situation was the Dr. Bott t7hub that has a few addt'l ports and features lots of milliamps with each port truly capable of 500ma thanks to its high amp adapter. They are orderable online or somewhat avail at apple stores if you call around price $42-$50 either with tax or shipping depending on where you live, i bought mine at an apple store as i did not want to wait for it to ship. If you think $45 sounds pricey, add up how much the regular no frills landline phone service costs for a year.