Digital ISDN 30 (Integrated Services Digital Network) lines are particularly suitable for businesses requiring simultaneous inbound/outbound calling capability and are completely flexible, easily accommodating growth and changing requirements within an organisation. For example, an organisation with 30 staff who has the requirement for each staff member to have their own inbound telephone number to receive calls, and with the need to make / receive in excess of 8 simultaneous calls should opt for an ISDN 30 over an ISDN2.