Apple's iPhone is the most selling electronics gadget worldwide. The iPhone 5 frenzy is hitting an all-time high with European carriers stockpiling nano-SIM cards (the new standard to be featured in the future smartphones) in advance, ahead of the launch. According to Verizon, the iPhone 5 is expected to release in Q4.

Citing multiple carrier sources, folks at Boy Genius Report claimed that Apple is supplying nano-SIM adapters to network carriers so that they can test the compatibility of the newly approved SIM standard with respective networks. The multiple carriers that BGR is talking about are unnamed in the report, but the publication confirms that AT&T is one of them. Apple wants carriers to deploy the standard and figure out any issues before mass production of the iPhone 5 begins.

Of late, we also came across reports that European carriers are stockpiling nano-SIM cards after ETSI approved the 4FF nano-SIM standard. The Nano-SIM is 40 percent smaller than micro-SIM, which is deployed in many of current generation smartphones.

Earlier this week, BGR also claimed that iPhone 5 is in EVT3 stage, a part of Engineering Validation Test process, and some time remains before the production kicks off. The tech site suggested that the iPhone 5 is arriving no earlier than late September.

In addition, the tech site also confirmed that the engineering prototype of iPhone 5 has 1GB of RAM, which is double than iPhone 4S's 512MB RAM, and comes with 4G LTE radios as well as an NFC chip.

Meanwhile, Verizon's Chief Financial Officer Fran Shammo dropped a hint about the release date of iPhone 5 during company's earnings release conference call on Thursday. Shammo indirectly confirmed the iPhone 5 October launch by saying that a big phone is dropping in during the fourth quarter this year.