The most common problem when it comes to iPhone text messaging is that it is not sending messages to your Android phone. The reason behind this problem is cellular service. If you have been having trouble receiving and sending texts from your Android device, here are some possible solutions. First, you can try switching to a different network. Check if the service is available in the country where you live. Second, you can switch your network settings to 2G or cellular data.

See also - https://emailspedia.com/why-is-my-iphone-not-sending-messages-how-to-fix/