Hi, this may not apply to you, but if you receive a lot of international calls, often, the incoming call does not have all the digits in the caller-id for iphone to match it with your contact book, so you are often left wondering who called (you can't search the address book for phone numbers, just names!). Very often, I feel the iphone should have been able to match the number (example, you have +91 11 23232323 in your address book and the incoming caller id drops just the + and even then, the iPhone fails to match).
So I wrote an app that lets you enter a number and it does a substring match to see which phone record maps to that number. Simple stuff. Hope it is useful to you.
Link:
iConverged iPhone Programming: Who Just Called Me?
Mini tutorial to access iPhone address book
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