What causes network connection failures during a call? July 08, 2022 11:14 Updated 1. This may be due to network congestion.2. Try calling a different contact to see if the problem still occurs.3. Try a different SIM card. Related articles What are the dimensions of Phone (1)? How does dual SIM work? Does the phone need to be restarted every day? What is OTG connection? What do I do if I've lost my phone?