I don't know of any plugin that will work in that manner - but what you describe would be a plugin that works with the end users IP address. The telephone number would correspond to the IP address of the person visiting the website. You may want to hire a coder to do this. You can use eLance.com to post this as a Plugin job.
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Not a graphics designer or coder, but can hack the code.
Love to create sites with Studiopress & Genesis Framework
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