My son had an iPhoneSE and we bought him an iPhone11. We did a factory reset on the old phone. But when we activated the new phone, it would not send text messages to any non-iPhone users. We fixed the problem when we put the SIM card from the old phone into the new one.
Why did this happen? And is there any reason we can't continue with the old SIM in the new phone? Is there any reason the new phone needs the new SIM? If so, how do we get the new SIM to work properly?