Apple has just released iOS 12.3.1 for download for iOS devices, which fixes bugs related to the Messages app and VoLTE (Voice over LTE) calls.

You can download this update by going to Settings > General > Software Update on your iOS device.

Direct downloads below:

• iOS 12.3.1 (Build 16F203) for:
  • iPad Air (Wi-Fi) (iPad4,1) — Download
  • iPad Air (Cellular) (iPad4,2) — Download
  • iPad Air (China) (iPad4,3) — Download
  • iPad mini 2 (Wi-Fi) (iPad4,4) — Download
  • iPad mini 2 (Cellular) (iPad4,5) — Download
  • iPad mini 2 (China) (iPad4,6) — Download
  • iPad mini 3 (Wi-Fi) (iPad4,7) — Download
  • iPad mini 3 (Cellular) (iPad4,8) — Download
  • iPad mini 3 (China) (iPad4,9) — Download
  • iPad mini 4 (Wi-Fi) (iPad5,1) — Download
  • iPad mini 4 (Cellular) (iPad5,2) — Download
  • iPad Air 2 (Wi-Fi) (iPad5,3) — Download
  • iPad Air 2 (Cellular) (iPad5,4) — Download
  • iPad Pro (9.7”, Wi-Fi) (iPad6,3) — Download
  • iPad Pro (9.7”, Cellular) (iPad6,4) — Download
  • iPad Pro (Wi-Fi) (iPad6,7) — Download
  • iPad Pro (Cellular) (iPad6,8) — Download
  • iPad 5 (Wi-Fi) (iPad6,11) — Download
  • iPad 5 (Cellular) (iPad6,12) — Download
  • iPad Pro 2 (12.9”, Wi-Fi) (iPad7,1) — Download
  • iPad Pro 2 (12.9”, Cellular) (iPad7,2) — Download
  • iPad Pro (10.5”, Wi-Fi) (iPad7,3) — Download
  • iPad Pro (10.5”, Cellular) (iPad7,4) — Download
  • iPad 6 (Wi-Fi) (iPad7,5) — Download
  • iPad 6 (Cellular) (iPad7,6) — Download
  • iPad Pro 3 (11”, Wi-Fi) (iPad8,1) — Download
  • iPad Pro 3 (11”, Wi-Fi, 1 TB) (iPad8,2) — Download
  • iPad Pro 3 (11”, Cellular) (iPad8,3) — Download
  • iPad Pro 3 (11”, Cellular, 1 TB) (iPad8,4) — Download
  • iPad Pro 3 (12.9”, Wi-Fi) (iPad8,5) — Download
  • iPad Pro 3 (12.9”, Wi-Fi, 1 TB) (iPad8,6) — Download
  • iPad Pro 3 (12.9”, Cellular) (iPad8,7) — Download
  • iPad Pro 3 (12.9”, Cellular, 1 TB) (iPad8,8) — Download
  • iPad11,1 (iPad11,1) — Download
  • iPad11,2 (iPad11,2) — Download
  • iPad11,3 (iPad11,3) — Download
  • iPad11,4 (iPad11,4) — Download
  • iPhone 5s (GSM/LTE) (iPhone6,1) — Download
  • iPhone 5s (CDMA/LTE) (iPhone6,2) — Download
  • iPhone 6 Plus (iPhone7,1) — Download
  • iPhone 6 (iPhone7,2) — Download
  • iPhone 6s (iPhone8,1) — Download
  • iPhone 6s Plus (iPhone8,2) — Download
  • iPhone SE (iPhone8,4) — Download
  • iPhone 7 (CDMA/GSM/LTE) (iPhone9,1) — Download
  • iPhone 7 Plus (CDMA/GSM/LTE) (iPhone9,2) — Download
  • iPhone 7 (GSM/LTE) (iPhone9,3) — Download
  • iPhone 7 Plus (GSM/LTE) (iPhone9,4) — Download
  • iPhone 8 (CDMA/GSM/LTE) (iPhone10,1) — Download
  • iPhone 8 Plus (CDMA/GSM/LTE) (iPhone10,2) — Download
  • iPhone X (CDMA/GSM/LTE) (iPhone10,3) — Download
  • iPhone 8 (GSM/LTE) (iPhone10,4) — Download
  • iPhone 8 Plus (GSM/LTE) (iPhone10,5) — Download
  • iPhone X (GSM/LTE) (iPhone10,6) — Download
  • iPhone XS (iPhone11,2) — Download
  • iPhone XS Max (iPhone11,4) — Download
  • iPhone XS Max (China) (iPhone11,6) — Download
  • iPhone XR (iPhone11,8) — Download
  • iPod touch 6G (iPod7,1) — Download