I had been using the app SMS Backup & Restore for quite a while. After getting a new phone and using the app to transfer the messages over as I was used to, I noticed some messages were missing.
I tried to find out why this was happening. It was because of a "new" message type called RCS: https://en.wikipedia.org/wiki/Rich_Communication_Services
Essentially those messages are stored in a separate database on the phone, hence not considered regular text messages.
Unfortunately SMS BR is not able to export this kind of messages (as of September 2021).
I didn't want to reinvent the wheel - there are already enough backup/restore apps for SMS and MMS. Instead I just wanted to make an app that was able to export the RCS messages, too. Preferably it should be a format that SMS BR could then import.
So if you're interested:
- Backup your SMS and MMS messages with another program.
- Import them on the target phone.
- Export the RCS using this app.
- Import those on the new phone as well.
- Technically the RCS will be converted to SMS messages.
- This program has only been tested with text messages. I don't know if images, etc. can be exported as well.