(Telecompaper) KPN has started a nationwide trial for calling over 4G. It expects to introduce the technology to customers next year. Up to now, 4G had only been used for data traffic. KPN is also testing 4G video calling with the technology, so that customers can switch during a call to a video call. The Dutch incumbent is looking at different types of handsets. It expects the number of users with a 4G phone to increase sharply over the coming months. KPN believes 4G will become the new standard for telephony. Around 3 million KPN customers currently use the operator's 4G network.