Yes. This recorder, and many others, are susceptible to interference from cell phone radios. In the DR-05x, it is a hardware issue, and therefore not related to any firmware revisions. I own five of these little units, and they work very well for my applications. I find the issue only shows itself when a phone (in my case an iPhone) gets within about 1.5-2 feet of the recorder when using the internal mics. With external sources, the problem may disappear entirely (with gain set low for line inputs), or vary depending on the quality of the cabling and external devices. I have other recorders, including my Sony PCM-D100 that can pick up the same interference, so we need to keep this in perspective. One cannot expect full RF filtration on a $100US recorder. This is part of why the likes of Sound Devices machines cost so much. In any case, the interference drops off geometrically with distance, so simply moving the devices apart a bit more (or using airplane mode) can quickly diminish the problem.