What Happens to an old cell phone after the number is transferred to a new cell phone?

I’m purchasing a new cell phone and I’m planning on transferring my old number to the new phone. However, a friend of mine is interested in buying the old phone from me and before I do any of this I’d like to know what will happen to the old phone’s number if I transfer it to my new phone. Will he have to transfer his number to that phone, or will it keep the number it already has regardless of me transferring it to the new phone?

Here’s another app that Shape Services has allowed me to review: Business Card Reader. Like the IM+ Pro app, I am no stranger to the business card reader, being a former windows mobile phone user, a business card reader came free with my previous Samsung Omnia mobile phone. This business card reader for the iPhone, however, doesn’t come for free but costs $ 3.99 at the app store. So, is it worth
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