New phone not showing all messages

[nicRob]

Bought a 2nd hand 6230 as an upgrade to my 3510i, but it's only showing 12 messages in inbox, whereas I actually have 46 (and that's the amount shown on my 3510i). Anyone got any ideas why this is, because I have no ideas at all

 

[nicRob]

My dad suggested that, but as far as I can see there isn't an option to select phone/sim for messages on 3510i. I'll have another look though.