If I use the search option in People it seems to search on both company name and surname but not phone numbers.
Is there a way to search for a phone number or part of a phone number in People?
This is not currently supported by the native People Hub application. The data is exposed to application developers, so there might be a third party app for doing this, although I'm not aware of one.
There is a third party app doing just that. It's called truedialer and is available to download for free at the marketplace: http://www.windowsphone.com/sv-se/apps/8f10c0bf-541b-47f5-a07e-1bffc785e7c1
I just tried it by writing my brothers 5 last numbers and it showed it right away. Clean and simple :)
No, but you can use the search in your Outlook (online version). Just go to the people hub and search the number.