OnePlus
Show Old SMS Messages Stored on SIM Card auf OnePlus
When you insert a SIM card from an older phone into a OnePlus device, text messages that were saved directly on the SIM chip do not appear in the regular conversation list right away. Android separates two storage locations for SMS: the internal phone storage and the SIM card memory. The Messages app defaults to showing phone storage first, so anything left on the SIM stays hidden until you open a dedicated view.
This mostly happens after a device change, a factory reset, or when a SIM card has been used across several phones over the years. The messages themselves are not lost, deleted, or corrupted. They simply sit in a separate memory area that needs a manual step to display.
To view them, open Open the Messages app ➔ Open the menu ➔ Open the Settings ➔ Choose a SIM card (Dual SIM) ➔ Tap on SIM card messages. On a dual SIM OnePlus phone, pick the SIM slot that held the old messages before switching cards. The list that opens shows every SMS still stored in that SIM memory, independent of what is already synced to the phone.
When this does not help
If messages were deleted from the SIM before the swap, or if the SIM itself was replaced by the carrier, this method will not recover anything, since the data is simply no longer on the chip. For messages that were backed up through a cloud service or a previous phone backup, restoring from that backup is usually faster than digging through SIM storage.