Call Unicom's mobile phone number, there is no prompt tone. I was disconnected directly, but I can send him a text message, but I can't make a phone call on someone else's cell phone. What happened? I

Call Unicom's mobile phone number, there is no prompt tone. I was disconnected directly, but I can send him a text message, but I can't make a phone call on someone else's cell phone. What happened? It is urgent. Connectivity problem. It is recommended that the mobile phone card be wiped with rubber. If you can't go to the business hall, call 100 10, and they will eat you. Connectivity leads to poor quality. I also encountered a network connection error when using the connection. I can't hear the sound when I answer the phone, and I hear unknown music. Seek adoption. Because network problems or my methods can generally be solved.