why is my iphone not sending text messages

The main reasons an iPhone may not send text messages include: Airplane Mode being turned on, no network connection, needing an iOS or app update, full storage, iMessage not set up or activated, MMS messaging being off, or outdated carrier settings. Troubleshooting steps involve restarting the iPhone, toggling Airplane Mode on and off, checking the network connection, ensuring iMessage and Send as SMS are enabled, resetting network settings, and updating carrier settings and iOS software. Additionally, selecting the correct SIM (if dual SIM) and verifying the phone number are important. Sometimes, removing and reinserting the SIM card or deleting and starting a new message thread can help. Incorrect date and time settings can also cause sending issues.