Caller name not visible

Hi everyone,
I'm a bit quizzed about a feature on my Jet which doesn't seem to be working right. Some of my contacts name appear when they call, and some others don't. The phonebook I copied from my old cellphone contained the country code(+230 for my country) for some contacts while others didn't, but when anyone from those two sets called, the name always appeared on my old cell. With the Jet it seems it guesses that a number with +230 1234567 and 1234567 is different. To fix that for my wife as a contact, i put the 2 numbers on the contact profile on different fields as "mobile, business". Now I don't have the issue when she calls, as her name appears each and every time.
I read somewhere that I should be adding the country code(+230) at the start of al my contacts number. BUt I have another contact in my phonebook already with +230 xxxxxxx as number, but he calls I have only the xxx xxxx on screen with no name of the caller. I just don't know what to do, but I'm sure that the idea i used for my wife contact profile can't be the only way out.

Please some help would be much appreciated.

Thanks