What should I do if someone is using a call sign? Just now, I heard a familiar call sign on channel 7050. I responded to him, but he didn't acknowledge me and continued with an automatic call recording. Normally, I can connect through two channels, but then I sent him the video I recorded via WeChat, and he said it wasn't him. He started using a high-powered device to play this recording from August 7th onwards, but he hasn't responded to anyone.