Earlier this morning it had appeared that the Sony Xperia Z4, Sony's upcoming flagship device to replace the elegantly designed Xperia Z3, was passing through Japanese regulations, having been certified by the Ministry of Internal Affairs in Japan according to blog of mobile. In that blog post, the Sony Xperia Z4 is referred to as having an FCC ID PM-0793-BV, so with an unknown Sony device passing through the FCC today listed with an FCC ID PY7-PM0850, some are asking the question "is this the Sony Xperia Z4?" At this point it's hard to tell, because there is nothing definitive to point to the fact that the Xperia Z4 is hitting the FCC at this time.
Mobile World Congress is at the end of next month and this is when Sony showed off the Xperia Z2 last year, so the rumors have been floating that this is the likeliest time frame for Sony to unveil their next flagship device for the year of 2015. Xperia Blog points out some details over the build number of the software for this unknown device, stating it was listed as running on firmware build number 25.0.A.0.33. This could matter because the firmware build number for the Lollipop build software that is supposed to hit the Sony Xperia Z3,(Sony's current flagship)is listed as 23.1.x.x.xxx.
The fact that this unknown device is listed as carrying a firmware with a higher build number doesn't necessarily mean anything at all, but it could point to a new Sony device running on Android Lollipop, and if the device is running Lollipop during certification and presumably launches with it, then it isn't entirely unreasonable to think it may be the Xperia Z4. Keep in mind though there is nothing to really support this theory, and it is just that at this point, a theory. As Mobile World Congress comes closer, we wouldn't doubt that we'd see more documentation or other information arise about Sony's new flagship device, so even if this information ends up being a completely different phone from Sony, it won't be long before actual documentation on the Xperia Z4 surfaces as it's just a matter of time.