The Phone Book module in ARCOS allows you to keep a contact list. You can add, modify, or delete contacts. You can also search the existing list. The Phone Book module is only a convenience for companies to use to keep contact numbers accessible. It does not interact with callouts in any way. It is text-based and for reference purposes only.
You can store local emergency numbers such as fire and police, or other contacts such as tree contractors, city water & sewer crews, etc. Depending on the numbers you store in the Phone Book, you should use caution to whom you give access.