SMS Forwarding from one iPhone number to another iPhone number only works when initial iPhone both on and unlocked. iMessage to the initial number (from someone with an iPhone) forwarding always works. Only SMS texts (from someone with an Android phone, for example). So if initial iPhone off, locked or out of juice, no SMS forward until I pier on and/or unlock.
Any suggestions on how to alleviate? Bummer to miss texts only from any non-iPhone user.
It makes sense the phone needs to be powered on. It can't receive the text or forward if it is powered off. IMessages are likely not being forwarded, you just have both devices set up to receive them. That is why it works when one device is powered off. I do not have that problem when my iphone is locked. It still forwards incoming texts to my ipad. So sorry, I have no suggestions on how to fix other than turn off forwarding and then re-enable. Once my forwarding just quit altogether until I did that and got it working again.
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.