How to solve the red word' undelivered' when iphone5 sends a text message?

See if there is anything wrong with the SMS settings. Baidu has initialization settings, mainly the service number of the SMS center, to see if there is a signal on the mobile phone and if the mobile phone card is in arrears.

Call 100 10 to report the failure of mobile phone service. Please ask the service personnel to inform the SMS center number and enter ##5005*7672 # to cancel the original wrong SMS center number.

Input: * 5005 * 7672 *+86 (130xxxxxxxxx correct SMS center number) # (long press 0 key to output+) Input: *#5005*7672# Check whether the number is entered correctly. Mobile phone settings page-general-network, turn off cellular data and 3G, mobile phone settings page-information -iMessage, power on and restart, turn on cellular data and 3G.