Nokia :: 5800 - Messaging Inbox - Phone Inbox Only Shows Number And Not Name

I've just bought a Nokia 5800 handset recently. It seems to me that even though I actually saved a contact's number in my phone, when he messages me the phone inbox only shows his number and not his name, even though I already saved his number under my phonebook.

Is there anyway to solve this such that it'll display his name instead? Its kind of pointless if I have to keep checking back to my phonebook to see who has messaged me, since I don't remember my friend's numbers and stuff.

On a note I saved all of my friend's number without the region number. That is as im living in Singapore, a contact's number would be saved as follows: 91234567 without the region code of +65. Thing is in my inbox all the phone number displayed shows the region code of +65 along with the number, but seriously even my super old phone can recognise that both 91234567 and +6591234567 are of the same person and displays the name correctly in the inbox.