I've just heard a rumor that my work phone number changed. So I go look in the address book and they've changed it. New prefix. Looks like they are changing it for the entire company. Or already have. Not that they've sent out an announcement, or notified the people whose numbers are changed. For a while the old number forwards to the new number. When the old number will no longer work I do not know.
Communication is this company's strong suit.
Also, if you have my work number, the prefix is now 679, not 564.