Our phones were reporting hardly any free memory despite the amount of used memory being a fraction of the 10Mb on the main phone itself. Deleting text messages didn't help - deleting a couple of messages actually made the free memory go down, leaving Emma's phone having no free memory at all. Copying the messages over to the memory card failed - possibly due to the lack of memory.

We used the Nokia Communicator software to back up the phone data, then reset the phone completely. This freed up all the memory but restoring the backup just got things back to where they were before. There was actually a tiny amount of free memory which allowed us to move the messages over to the memory card, deleting them from the phone memory. This did the trick, giving around 8Mb of free memory, despite the File Manager only claiming the messages took up less than 2Mb.

The free memory decreasing when we deleted texts is still a mystery but at least we now know why the phone was full. Each text message must take up more memory than is reported. The phone treats it's internal memory as a disk drive and if each message is stored as a seperate file then this will explain it. Files always take up a minimum size, often around 2-4Kb, so a message which is only a few characters long will still take up a few K.