This enables a phone field AND a fax field for the company (client) module (contacts already have a phone, fax and mobile field). If you enable this field, simply edit a company to input the company phone and fax details.
By default, Accelo does not allow contacts to be added on their own. This is primarily because the features of the system are optimized for managing work for a company, and linking a contact where necessary.
If your business is primarily providing services to other businesses, then you should leave this option set to No. However, if you are frequently dealing with individuals as clients, then it may be easier for your staff to manage stand-alone contacts.
To allow stand-alone contacts, change this setting to Yes. You will then see the Add option under the Contact navigation.
This is a global default setting. Users can update their preferences from their settings page (click your Username > Settings).
Functionally this means that when a user (with email capture enabled) receives an email from an unknown contact, this contact will be added into Accelo if the sender's email domain matches that of an existing contact. Hence this can save your staff time by automatically creating contacts who appear to be colleagues of existing client contacts.